Surface Tracker "Flattens" Wafers
Elk Grove Village, IL — May 3, 2016
Silicon wafers are supposed to be "flat" when they are being scanned by an acoustic micro imaging tool for defect detection or for measurement. Die having defects will be removed after dicing.
But suppose the wafer is warped. Ordinarily, the acoustic tool’s transducer scans in a flat plane, and is focused and gated on a specific depth of interest. Warping of the wafer means that some die are partly or entirely out of focus and defects can be entirely missed.
Sonoscan has solved this problem in its C-SAM® systems with its new Quantitative Dynamic Z™ (Q-DZ) surface tracking feature for scanning warped wafers. The tool acquires data from the scans that not only reveal the features inside the wafer but also measures the warpage. The warpage information is used during the scan to instantly adjust the height of the transducer above the wafer surface and maintain the critical focus inside the wafer over its entire area.
The result is that the transducer scans a wafer whose topography resembles rolling hills, but the transducer sees it as a flat plain. All devices are imaged at the depth of interest, all internal features remain in focus and within the gate, and all rejects are identified without any false rejects due to warpage.
In addition, the Q-DZ outputs a series of contour coefficients/parameters that can be used to monitor processes in manufacturing, for example, encapsulant cure rates, internal stresses, etc.
Sonoscan, Inc. 2149 E. Pratt Blvd., Elk Grove Village, IL 60007. Phone 847-437-6400. Contact Bill Zuckerman x237. Email firstname.lastname@example.org; web www.sonoscan.com.
About Sonoscan®: Sonoscan is the leading developer and manufacturer of acoustic microscopes and sophisticated acoustic micro imaging systems, widely used for nondestructive analysis of defects in industrial products and semiconductor devices. For over 30 years, Sonoscan’s attention to customer needs and investment in R&D has created systems that set industry standards for speed and accuracy. Key products include C-SAM® systems for off-line and laboratory analysis and FACTS2™ for automated production inspection.
Through its SonoLab division Sonoscan applications engineers, with experience totaling more than two centuries in acoustic microscopy, assist hundreds of customers annually in solving materials problems and quality control issues. SonoLab operates applications testing laboratories in multiple global locations to serve the inspection needs of customers that do not have their own capability.