International Business Machines Corporation

Sandi E Merritt

Charles Jesse Taft

Richard O Henry

David F Hilscher

Robert W Zigner, Jr

A recyclable fluid cleaning system wafers includes a cleaning vessel configured to clean semiconductor wafers immersed in a bath of persulfuric acid cleaning solution, the cleaning solution circulated through a primary process tool fluid path; a secondary fluid path that diverts a portion of the persulfuric acid cleaning solution for electrolysis treatment thereof; an electrolysis reactor within the secondary fluid path that receives oxidant depleted sulfuric acid, the electrolysis reactor having electrodes that, when activated causes sulfate ions in the solution to be oxidized and form persulfate ions that are recombined with fluid from the primary fluid path and fed back to the cleaning vessel; and one or more controller devices in operative communication with the cleaning vessel and with the electrolysis reactor.

Partial solution replacement in recyclable persulfuric acid cleaning systems

A method of implementing cleaning solution replacement in a recyclable fluid cleaning system for semiconductor wafers includes activating electrode current for an electrolysis reactor included in the cleaning system. At least one of electrode voltage and operating time for the electrolysis reactor is monitored, until a trigger point has been reached. The trigger point includes one of the electrode voltage reaching a predetermined threshold voltage value, a process time counter reaching a predetermined counter value, and a time value that the electrode voltage has been at the threshold voltage value reaching predetermined value. The process time counter is incremented based on one or more of actual wafer processing time, wafer type, number of wafers processed, and thickness of material to be stripped. Upon reaching the trigger point, the electrode current is deactivated, and at least a portion of cleaning system fluid is drained and replaced with fresh cleaning fluid.

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Cold Spring, NY, United States of America

Sandi E Merritt