Closed loop concentration control system for chemical mechanical polishing slurry

• Main Authors: LAI CHIEN-HSIN, LIN JUEN-KUEN, YU KEVIN, LI HUANG-YI
• Format: Patent
• Language: English
• Published: 13.04.2004
• Edition: 7
• Subjects: DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GRINDING; MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; PERFORMING OPERATIONS; POLISHING; TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION; TECHNICAL SUBJECTS COVERED BY FORMER USPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS; TRANSPORTING

Polishing slurry is transported via piping to flow into the closed loop control system. First, the polishing slurry flows into the ultrasonic concentration detector. Original data of the polishing slurry that is determined by means of ultrasonic concentration detector is a fluid velocity at that time. This determined value can be converted into weight percent concentration at that time by memory data table. The converted data of weight percent concentration will be transmitted into program logic controller (PLC), and the data of liquid level volume in the distribution tank will be transmitted into program logic controller at present. The program logic controller will then analyze whether the quantity of oxidant is sufficient. If the quantity of oxidant does not reach the required criterion, the program logic controller will control the analog valve to transmit a supplementary quantity of oxidant into the distribution tank via the analog valve and piping.