Browse Prior Art Database

WATER SEAL CHUCK FOR POLISHING OF SEMICONDUCTOR WAFERS

IP.com Disclosure Number: IPCOM000007174D
Original Publication Date: 1994-Jun-01
Included in the Prior Art Database: 2002-Mar-01
Document File: 1 page(s) / 72K

Publishing Venue

Motorola

Related People

Otto Luedke: AUTHOR [+3]

Abstract

Wafers are typically polished on a Robot Assisted Polish Systems (RAPS) one wafer at a time to give maximum control of the flatness of each individual wafer and are supported by a flat rigid vacuum chuck during the polish operation.

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MO-LA Technical Developments Volume 22 June 1994

WATER SEAL CHUCK FOR POLISHING OF SEMICONDUCTOR WAFERS

by Otto Luedke, Fernando Bello and Cindy Welt

  Wafers are typically polished on a Robot Assisted Polish Systems (RAPS) one wafer at a time to give maximum control of the flatness of each individual wafer and are supported by a flat rigid vacuum chuck during the polish operation.

  The seal between the wafer and the vacuum chuck is typically not perfect, and the pressure gra- dient from the perimeter of the wafer to the vacuum passage forces some slurry to seep into the vacuum passages of the chuck. There the liquid portion of the slurry evaporates, leaving behind silica deposits on the wafer and on the chuck.

  The deposits lefi behind on the wafer can be difficult to remove in the post polish chemical clean process. If the deposits cannot be removed by repeated passes through the clean process, they are downgraded and sold as lower cost, looser specitica- tion product (i.e. test wafers).

  The deposits letI behind on the chuck present a more serious problem. They clog the vacuum pas- sages, and eventually build up to form a protrusion on the surface of the chuck. Subsequent wafers will conform to this protrusion, transferring the bump through to the soon to be polished surface. The pol- ish operation results in a flattening of the polished

surface, but as soon as the wafer is released from the chuck, the unpolished surface springs back to its original shape, thus lea...