Speaker: Dr. Stefan Behler, Senior Expert Process Engineer, Besi Switzerland AG
Presentation Slides: “How To Peel Ultra Thin Dies From Wafer Tape” (1 MB PDF)
Meeting Date: Thursday, December 7, 2017
Time: 11:30 AM Registration (and sandwiches/drinks); 12:00 PM Presentation
Presentation-only: 12:00 noon (come at 11:45)
Cost: $5 IEEE members. students, unemployed, $10 non-members
Location: Texas Instruments Building E Conference Center, 2900 Semiconductor Dr. (off Kifer Rd), Santa Clara
Summary: The four major key properties for successful, damage-free ultra-thin die (< 50 um thick) pickup from a wafer foil are described in detail: die bending stress, die strength, edge peel force, and bulk peel force. First, bending stress for different pickup methods (multi stage, multi disc, multi needle) are calculated and compared using a dynamic FEA model. Second, we summarize how the die strength is influenced by die structures and wafer processing steps, especially by thinning and dicing methods. In addition, we present die strength measurements for TSV test dies. Third, the property "wafer foil edge peel force" is introduced, and the dependency on the dicing method is experimentally verified. It clearly shows, that dicing-before-grinding is to be preferred over single cut dicing. Fourth, we give an overview of bulk peel forces of various commercial wafer foils. Values are taken from datasheet specifications, and compared using Kendall’s equation.
Bio: Stefan Behler received his M. S. in experimental physics from the University of Göttingen (Gemany) in 1990, and his Ph.D. in physics from the University of Basel (Switzerland) in 1994. He was awarded an Alexander von Humboldt fellowship for a 2-year research project at the Lawrence Berkeley National Laboratory. The project was aimed at the investigation of surface chemistry of noble metals. In 1996 he joined the company Besi (formerly ESEC) focusing on process technology of die bonding. He is currently project manager for ultra-thin die applications at Besi Switzerland.