METHOD AND APPARATUS FOR REMOVAL OF CARBON DIOXIDE FROM CORROSIVE GASES
Publication Date: 2009-Sep-02
The IP.com Prior Art Database
Disclosed herein are non-limiting embodiments of methods, apparatus and compositions utilized in the manufacture of semiconductor, photovoltaic, flat panel and LCD-TFT devices.
A method and apparatus for removal of carbon dioxide from corrosive gases, particularly, halogenated gases such as pure HCl, HBr, Cl2, Br2, etc., is proposed and described in some embodiments of the invention. Using appropriately conditioned corrosive gas resistant adsorbents, such as acid washed activated carbons or high silica to alumina ratio zeolites (typically, silica:alumina 10 and higher), maintained at either ambient temperature or appropriately cooled, CO2 can be removed from corrosive vapor streams from typical 50-100 ppm down to below 1 ppm concentration level. Individual adsorbents, or their combinations, to maximize the adsorptive capacity and optimize adsorbent regeneration, can be used for CO2 purification from the vapor streams of corrosive gases. Besides the correct choice of adsorbents, properly optimized preconditioning procedures are critical for the described purification method. Typical conditioning sequences could include corrosive gas flush, static exposure to corrosive vapor, inert gas purge, extended vacuum purge. All preconditioning stages could be performed at either ambient temperature or while heating the conditioned adsorbents.
In some embodiments, the described invention relates to the preparation of high purity corrosive gases. Many of these gases (anhydrous HCl, HBr, Cl2, Br2, BCl3, etc.) are used in different steps of semiconductor fabrication as etching and cleaning media. The typical gas purity requirements for these processes are specified in the single ppm range for most gas contaminants, such as CO, CH4, N2, H2O, CO2 and others. However, most of the industrial methods used for making these corrosive halogenated gases provide just commodity grade purity with level of contaminants in tens to thousands of ppm. Hence additional purifying stages are necessary to manufacture these gases at ppm and better purity.
A number of various techniques have been developed to remove some of the mentioned contaminants from different corrosive gases to the needed ppm levels. Distillation is often used to remove volatile (light) impurities such as CO, N2, CH4, CO2 from gas corrosive matrixes. Vapor phase trans-filling, on the other hand, can be effectively employed to purify these gases from many metal impurities and, to lesser extent, moisture depending on the gas. Sparging an inert gas (typically He) through the liquefied corrosive gas is another way to remove volatile (light) impurities from corrosive gas streams. Distillation, vapor phase trans-filling and sparging are currently used to pre...