Wafer integrated rigid support ring

US6706621B2 · kind B2 · utility

Assignee

• International Business Machines Corporation · US

Inventors

• Harry D. Cox · Rifton, US
• David Daniel · Burlington, US
• Leonard Gardecki · Saint Johnsbury Center, US
• Albert Gregoritsch · Jericho, US
• Ruth Machell Julianelle · Underhill, US
• Charles Keeler · South Burlington, US
• Doris Pulaski · Holmes, US
• Mary Schaffer · Hopewell Junction, US
• David Smith · Pleasant Valley, US
• David J. Specht · San Jose, US
• Adolf E. Wirsing · South Hero, US

Key dates

• Filing date: Nov 22, 2002
• Grant date: Mar 16, 2004
• Expiry date: Nov 22, 2022

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01L2924/15787
• WIPO field: Semiconductors
• WIPO sector: Electrical engineering

Abstract

A shadow mask for depositing solder bumps includes additional dummy holes located adjacent holes corresponding to most of the perimeter chips of the wafer. The additional dummy provide more uniform plasma etching of contacts of the wafer, improve etching of contacts of perimeter chips, and lower contact resistance of contacts of perimeter chips. The extra holes also provide solder bumps outside the perimeter chips that can be used to support a second shadow mask for deposition of an additional material, such as tin, on the reflowed solder bumps for mounting the chips on a plastic substrate at low temperature. An improved mask to wafer alignment aid is formed from standard solder bumps. The improved alignment aid avoids damage to test probes and provides improved course alignment.