Unique Sensor Film Minimizes Defects and Improves Quality in Wafer Bonding
Product News Oct 27, 2009
Pressurex® film from Sensor Products Inc. is a way to detect and correct pressure variations which can result in flaws (defects) in the wafer bonding process. When placed between contacting surfaces, it instantaneously and permanently changes color directly proportional to the actual pressure applied.
With Pressurex®, variations in pressure that lead to imperfections (or irregularities) in the bonding process can be detected and corrected - improving yield, decreasing scrap, and boosting productivity.
In wafer bonding, two flat substrates are permanently joined together by applying carefully calculated pressure, temperature, and voltage. Of the three parameters, pressure is often the most difficult to ascertain and control. Traditional methods assume perfectly flat pressure plates.
However, in nearly all real environments pressure plates are not ideal due to manufacturing or installation variability and degradation over time from wear. The result is difficult to detect pressure variations across the surface that can lead to un-bonded wafer areas, cracked wafers, and premature wear of the pressure plates.
Pressurex® systematically measures pressure across the entire pressure plate. When placed between contacting surfaces of the wafer bonding fixture, the film instantaneously and permanently changes color directly proportional to the actual pressure applied.
Precise pressure magnitude is determined by comparing color variation results to a color correlation chart (conceptually similar to interpreting Litmus paper). Additional pressure analysis of the film is available which assimilates the pressure distribution into 2-D and 3-D pseudo color images, histograms and line scans among other features.
Wafer-to-wafer bonding has become an enabling semiconductor technology in industries such as 3D packaging, MEMS, MOEMS, and SOI. Pressurex® is being used across a wide range of bonding technologies, including metal eutectic, anodic, fusion, metal diffusion, glass frit, and polymer adhesive bonding.
The “snapshot” imaging results of Pressurex® can be used as a control to compare processes and tools, making it ideal for six-sigma and other closely monitored high performance manufacturing operations.