| 摘要 |
<p>#CMT# #/CMT# Preparation of a gas or a gas mixture containing molecular fluorine from a gas or a gas mixture of fluorine derivative, comprises decomposing fluorine gas (mixture), particularly nitrogen trifluoride by passing a high density hot electron plasma at atmospheric pressure or a pressure close to it, to obtain a maximum temperature (T max) higher than 2000 K of the heavy species in plasma, cooling the mixture of the various species in plasma to a temperature (T h) followed by rapid cooling to obtain a gas mixture containing of fluorine in molecular form. #CMT# : #/CMT# Preparation of a gas or a gas mixture (I) containing molecular fluorine from a gas or a gas mixture (II) of fluorine derivative, comprises decomposing (II), particularly nitrogen trifluoride by passing a high density hot electron plasma at atmospheric pressure or a pressure close to the atmospheric pressure to obtain a maximum temperature T max higher than 2000 K of the heavy species in plasma, cooling the mixture of the various species in plasma to a temperature T h, then rapid cooling between T h and T b (where T h and T b are two temperatures determined in experiments according to gas or the gas mixture containing fluorine, T h is the temperature from which the gas molecules or mixture of gases initially injected into plasma can start to be reformed from their dissociation fragments and T b is the temperature to which more than 90% of the fluorine atoms resulting from dissociation in plasma recombined) to obtain (I). An independent claim is included for a fluorinated gas generator delivering (I), comprising a source of nitrogen trifluoride in gaseous form, generators of a high density hot electron plasma to decompose the fluorinated gas molecules and to generate a plasma at a maximum temperature of the heavy, neutral and ionic species T max higher than 2000 K, cooling unit for the gas mixture resulting from the decomposition and recovery unit of the gas mixture containing fluorine molecules cooled at temperature lower than T b. #CMT#USE : #/CMT# (I) is useful in the cleaning of semiconductor production equipments. #CMT#ADVANTAGE : #/CMT# The process is easy to implement and is industrially applicable. #CMT#DESCRIPTION OF DRAWINGS : #/CMT# The figure shows a schematic representation of the device for preparing molecular fluorine. #CMT#INORGANIC CHEMISTRY : #/CMT# Preferred Process: The maximum temperature of the heavy species (ions and neutrals) in the discharge generating plasma is 3000-10000 K. The density of electrons of plasma is higher than 10 12> electron/cm 3>, preferably 10 12>-10 15> electrons/cm 3>. The duration of rapid cooling between the temperatures T h and T b is =5x10 -2> s, preferably =5x10 -3> s to avoid a substantial reformation of the initial species and to support the formation of fluorine molecules (F 2). The fluorinated gas is nitrogen trifluoride (NF 3), where T h is approximately 1200 K and T b is approximately 800 K. The plasma is plasma close to thermodynamic balance and in particular a plasma generated by radio waves in mode of inductive coupling or microwaves. The plasma is formed at atmospheric pressure or close to the atmospheric pressure with a variant of 10 4>- 10 6> Pascal. (II) is mixed with a first gas preferably inert, before the stage of cracking. (II) is diluted using a second gas, particularly an inert gas during or after the cracking of (II). The temperature of second gas is such as it makes it possible to carry out at least partially the rapid cooling optionally necessary to support the formation of molecular fluorine. The gas mixture after cooling is mixed with a third inert gas. Preferred Components: The first, second and/or third gas are nitrogen, argon, helium, krypton, xenon, carbon dioxide, carbon monoxide, nitrogen oxide and/or hydrogen. (I) comprises of 75 mol.% up to 1 ppm of molecular fluorine. (I) is contacted with a surface or a volume. #CMT#INSTRUMENTATION AND TESTING : #/CMT# Preferred Components: The generator further comprises an inert gas source such as a source of nitrogen, argon and/or helium. The generator further comprises mixing unit of the gas mixture with a second gas e.g. an inert gas or gaseous hydrofluoric acid. #CMT#POLYMERS : #/CMT# Preferred Components: The surface or volume is polymeric and/or dielectric metallic materials.</p> |
