Athens Corporation

David W Persichini

Joe G Hoffman

R Scot Clark

John B Davison

Wallace I Yuan

Bruce A Lipisko

Alan W Jones

Allen H Jones, Jr

John Andrew Adams

Gerald A Krulik

Christopher S Blatt

Alan H Jones

A method for the on-site reprocessing of isopropyl alcohol used in semiconductor manufacturing, to generate an ultradry and ultrapure isopropyl alcohol. This ultradry and ultrapure isopropyl alcohol is produced through a pervaporation step, followed by double distillation. In the first distillation step, an autonomous azeotropic self-stripping distillation column is used to produce an ultradry and partially purified isopropyl alcohol. In the next step, the isopropyl alcohol is distilled in an overhead product distillation column, to produce an ultrapure and ultradry isopropyl alcohol. Alternatively, if the feed isopropyl alcohol contains less than 2000 ppm water, the pervaporation step may be omitted. The resulting isopropyl alcohol has between a high of 100 parts per million (ppm) and a low of 0.1 ppm of water in the isopropyl alcohol. It also has zero particles per milliliter of a size larger than 2.0 microns, zero to 2 particles per milliliter of a size of 0.5 micron to 2.0 microns, zero to 30 particles per milliliter of a size between 0.1 microns and 0.5 microns, an unspecified number of particles per milliliter below 0.1 microns, 1 part per trillion (ppt) to 1 part per billion (ppb) of any specific trace impurity such as metals, anions, and cations, and 10 ppt to 10 ppm of any other specific trace organic substances.

Dehydration and purification of isopropyl alcohol to an ultradry and

Method and apparatus for the distillation of liquids which is particularly suited for the removal of soluble impurities and insoluble and non-volatile particles of 10 microns to 0.2 micron or less in size. A substantially elongated distillation chamber having walls equipped with axially disposed concentric boiling rings spaced from the walls near the bottom, and a packing stop, packing redirector rings for condensed vapor, and a reflux condenser in the upper part of the distillation chamber provide, during distillation, a smooth convective upward flow of distilling liquid and vapor proximate the walls and boiling rings and a smooth convective downward flow of distilling liquid and vapor substantially centrally of the distillation chamber.

Apparatus for the continuous on-site chemical reprocessing of ultrapure

Method for the production of ultrapure sulfuric acid including distillation of sulfuric acid material for the removal of soluble impurities and insoluble and non-volatile particles of 10 microns to 0.2 micron or less in size. Reprocessing is also provided. Distillation takes place in a distillation chamber having walls which are provided with means within the chamber to provide smooth convective upward flow of distilling liquid and vapor proximate the walls and means for smooth convective downward flow substantially centrally of the distillation chamber. Redirection means and packing together with reflux means insure the washing of rising vapor and direct the condensing vapor substantially centrally of the distillation chamber. Ultrapure sulfuric acid is also provided having 5 or less particles per cubic centimeter of a size of 0.5 micron and larger and less than 10 ppb of any specific trace impurity such as cations.

Method for making ultrapure sulfuric acid

An improved wafer cleaning process wherein a novel oxidant solution comprising ultrapure sulfuric acid, peroxydisulfuric acid, and ultrapure water used in a semiconductor wafer cleaning process is continuously withdrawn after use. The withdrawn oxidant is reprocessed continuously by contacting with alumina to remove fluoride ions. Water is continuously separated or stripped from the oxidant solution by heating the solution and bubbling an inert gas therethrough. The separated oxidant is continuously distilled and condensed to form a purified stream of sulfuric acid. The major portion of this stream is continuously returned to the wafer cleaning process. The remaining minor portion is continuously cooled, subjected to analysis for purity, and diluted with ultrapure water prior to electrochemical treatment in the anode compartment of an electrochemical cell. This converts at least a portion of the dilute sulfuric acid to peroxydisulfuric acid. The resulting solution is continuously returned to the wafer cleaning process to be mixed with the major portion of the purified sulfuric acid.

Method and apparatus for the continuous on-site chemical reprocessing of

A continuous process and apparatus for the repurification of ultrapure liquids. An oxidant solution comprising ultrapure sulfuric acid, peroxydisulfuric acid, and ultrapure water is continuously withdrawn from a process after use. The withdrawn oxidant is reprocessed continuously by contacting with alumina to remove fluoride ions. Water is continuously separated or stripped from the oxidant solution by heating the solution and bubbling an inert gas therethrough causing the water to vaporize from the solution. The separated oxidant is continuously distilled and condensed to form a purified stream of sulfuric acid. The major portion of this stream is continuously returned to the process. The remaining minor portion is continuously cooled, subjected to analysis for purity, and diluted with ultrapure water. The diluted sulfuric acid is further cooled prior to electrochemical treatment in the anode compartment of an electrochemical cell. This converts at least a portion of the dilute sulfuric acid to peroxydisulfuric acid. The resulting solution is continuously returned to the process to be mixed with the major portion of the purified sulfuric acid. A system of apparatus to conduct the processes is provided which also includes means for continuously analyzing the minor portion for purity and trace elements.

Growing community of inventors

Oceanside, CA, United States of America

David W Persichini