Browse Prior Art Database

IN-LINE, POINT-OF-USE SLURRY FLOW DETECTION

IP.com Disclosure Number: IPCOM000008025D
Original Publication Date: 1997-Mar-01
Included in the Prior Art Database: 2002-May-13
Document File: 3 page(s) / 124K

Publishing Venue

Motorola

Related People

James Grootegoed: AUTHOR [+2]

Abstract

In this work, we discuss the apparatus and installation plan required for in-line, point-of-use slurry flow detection for use with Chemical Mechanical Polishing tools; specifically, the IPEC Planar 472 Polisher. The apparatus and methodolo- gy presented herein is also applicable to both metal and oxide polishers from any of the recognized Suppliers of this type of tool.

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M-LA Technical Developments

IN-LINE, POINT-OF-USE SLURRY FLOW DETECTION

by James Grootegoed and James Vanell

ABSTRACT

  In this work, we discuss the apparatus and installation plan required for in-line, point-of-use slurry flow detection for use with Chemical Mechanical Polishing tools; specifically, the IPEC Planar 472 Polisher. The apparatus and methodolo- gy presented herein is also applicable to both metal and oxide polishers from any of the recognized Suppliers of this type of tool.

STATEMENT OF PROBLEM

  Chemical mechanical polishing requires the use of various slurry formulations. These shnry mixes are chemically and/or mechanically aggressive liq- uids that typically are pumped in pulsing flows with diaphragm or peristaltic pumps. The flow rates are normally low at approximately 75 ml to 175 ml per minute.

  The combination of chemical and mechanical slurry mix aggressiveness and the low, pulsing flows make the standard methods of flow detection not reliable. These methods include: float-position sensors, infrared sensors, fixed orifice flow switch-

es, magnetic flowmeters, turbine flowmeters, and ultrasonic doppler flowmeters. Standard practice by the CMP tool Suppliers is to monitor slurry flow via slurry pump motor encoder counts. This is very indirect and only monitors pump motor perfor- mance.

  The undetected loss of slurry flow can result in very costly problems including unscheduled down- time and loss of production as well as equipment and product damage and/or loss.

SOLUTION TO THE PROBLEM

  The on-board detection of slurry flow is accom- plished via the use of a commercially-available thermal dispersion flow switch that, paired with a vortex chamber, allows the detection of very low slurry flow rates and/or pulsating flows.

  The switch works by the temperature differen- tial between two temperature probes, one of which is heated while the other floats with the temperature of the surrounding liquid...