The characteristics and factors of a wafer dicing blade and its optimized interactions required for singulating high metal stack lowk wafers

摘要

Dicing a thick, 6 metal layer low-k Cu metallization wafer (from 90nm node wafer technology) is very challenging compared to the 4 metal layer stacked wafer. Poor topside cutting responses with excessive saw chip-outs were observed with the 6 metal layer. To resolve the saw chipping quality issue, a series of dicing assessments were performed, which includes: (1) saw machine baseline calibration and verification, (2) analysis study on the blade's elements (diamond grit, diamond concentration, bond type) (3) new saw blade selection and evaluation, and (4) saw process parameter optimization and validation. This paper is focused on discussing the fundamentals of understanding each of the blade elements and its interaction on improving the topside chipping and peeling quality. Experimental studies were conducted by using various blade types and by varying the blade element composition. This includes variations in diamond grits sizes, diamond concentration (higher vs. lower diamond concentration), and bond type (softer vs. harder bond). A thorough process characterization was conducted to validate the cutting performance on the post-processed wafers. All results and data collected from the experimental studies were statistically analyzed and interpreted. In conclusion, a new saw blade with the appropriate selected blade attributes were introduced and qualified. With the optimized blade and saw parameters for the thick low-k Cu metallization wafers, topside chipping and peeling quality was significantly improved.