초록 ▼

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acid, peroxydisulfuric acid, and ultrapure water used in a semiconductor wafer cleaning process is continuously withdrawn after use. The withdrawn oxidant is reprocessed continuously by contacting with

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acid, peroxydisulfuric acid, and ultrapure water used in a semiconductor wafer cleaning process is continuously withdrawn after use. The withdrawn oxidant is reprocessed continuously by contacting with alumina to remove fluoride ions.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.

대표청구항 ▼

In a process for the acid cleaning of semiconductor wafers wherein said wafers are exposed to an oxidant solution for a period of time and at a temperature sufficient to remove contaminants therefrom, the improvement which comprises: using as the oxidant solution an ultrapure oxidant solution compri

In a process for the acid cleaning of semiconductor wafers wherein said wafers are exposed to an oxidant solution for a period of time and at a temperature sufficient to remove contaminants therefrom, the improvement which comprises: using as the oxidant solution an ultrapure oxidant solution comprising ultrapure sulfuric acid, ultrapure peroxydisulfuric acid, and ultrapure water which is produced according to a continuous process for the reprocessing and repurification of said ultrapure oxidant solution comprising: withdrawing at least a portion of said oxidant solution used in the semiconductor wafer cleaning process; distilling said withdrawn oxidant solution to remove particles and dissolved impurities to form ultrapurified sulfuric acid; dividing said ultrapurified sulfuric acid into a major portion and a minor portion; returning said major portion of said ultrapurified sulfuric acid to said semiconductor wafer cleaning process; diluting said remaining minor portion of said ultrapurified sulfuric acid with ultrapure water to produce a continuous stream of diluted ultrapure sulfuric acid; introducing said diluted ultrapure sulfuric acid into the anode compartment of an electrochemical cell where at least a portion of said diluted ultrapure sulfuric acid is converted into ultrapure peroxydisulfuric acid; adding at least a portion of said resulting solution of ultrapure sulfuric acid, ultrapure peroxydisulfuric acid, and ultrapure water to said semiconductor wafer cleaning process where it is admixed with said major portion of said ultrapure sulfuric acid to reform said ultrapure oxidant solution.