Browse Prior Art Database

SF6/02 PLASMA ETCH AND CONTAMINATION ETCH

IP.com Disclosure Number: IPCOM000006350D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2001-Dec-27
Document File: 1 page(s) / 62K

Publishing Venue

Motorola

Related People

John Nichols: AUTHOR [+2]

Abstract

The mechanically thinning (back grinding or lap- ping) of silicon wafers near the end of the process flow, permits the majority of the wafer semiconductor processing steps to be performed with thicker wafers (>20 mils) which are more resistant to breakage. The thinning step usually reduces wafer thicknesses to a range of 11 to 15 mils, or less.

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MOTOROLA INC. Technical Developments Volume 14 December 1991

SF6102 PLASMA ETCH AND CONTAMINATION ETCH

by John Nichols and Terry Weaver

THE PROBLEM

  The mechanically thinning (back grinding or lap- ping) of silicon wafers near the end of the process flow, permits the majority of the wafer semiconductor processing steps to be performed with thicker wafers (>20 mils) which are more resistant to breakage. The thinning step usually reduces wafer thicknesses to a range of 11 to 15 mils, or less.

  The thinning process leaves mechanical damage on the backs of the wafers which reduces their mechanical strength. This leads to increased wafer breakage during subsequent processing steps. Further, individual chips cut from these mechanically weaker wafers, are more prone to crack during assembly or packaging operations. Such weaker semiconductor chips could even create reli- ability problems in customer applications.

  Removing this damage by wet chemical etching dra- matically increases the die strength of the wafer. How- ever, this technique usually requires wafer front side protection, is non-uniform and is costly.

  Plasma etch using SF6 eliminates the need for front side protection, improves uniformity, and reduces costs. This process appears to eliminate the problems associated with wet etch, but some problems still remain. Frequent

and lengthy cleaning of the etch chambers and equip- ment are required to remove sulfur residue. Further, sul- fur is implanted into the surface...