Grinding thin wafers (less than 150 um) on an old grind tool model may not be a great pleasure. Either an extra process step (etching) may need to be introduced or a new capital investment needs to be made to improve the yields.
In order to increase the yields of thin wafer grinding on existing and new machine tools, we offer state of the art technology wheels.
Selecting a proper coarse grind wheel becomes very important for thin wafer grinding. If the sub surface damages left behind by the coarse wheels are not completely removed with the fine grind step, the wafer yield losses may go up significantly.
The coarse grind wheel needs to be gentler on the wafer as well as have lesser tendency to leave behind residual stresses. The abrasive grain size also needs to be properly selected to reduce the amount of sub surface damage inflicted on the wafer.
Depending on the grind tool model as well as the incoming wafer quality and characteristics, we offer customized solutions for the optimum results.
In an effort to improve the process of grinding thin wafers, it was essential to develop wheels that impart minimal sub-surface damage and residual stress to the wafers during grinding. Such a wheel could potentially reduce or eliminate the need for a post-grinding stress relief operation.
The team recently introduced a next generation #8000 (#6000 & #4000 also available) wheel that provides a very smooth surface finish leading to improved wafer and die strength. Because of lower surface stresses, the bow on the ground wafers is also reduced. In-house tests have demonstrated promising results with this new, revolutionary abrasive tool (#8000/#6000/#4000) that can be used to replace the regular #2000 wheels on existing machine tools to grind thinner wafers or to obtain better wafer quality to reduce post-grind operations such as polishing or etching.
The anticipated benefits of the thin wafer grinding wheels using this new technology from Norton Winter Electronics are:
• Improved wafer and die strength
• Improved surface finish and integrity
• Reduction of wafer bow and warp
• Improved wafer handling on existing machine tools
• Potential reduction in post-grinding operations such as polishing or etching to relieve stress
• Potential reduction in overall process cost
|Specification||Norton winter mesh||Ra ()||Estimated Life*|
|Polish#1 bxl6550||8000||20 - 30||40 to 50|
|Polish#1.5 bxl6550||6000||25 - 35||50 to 60|
|Polish#2 bxl6550||4000||30 to 45||70 to 90|
|Polish# 3 in bx623d||2000||50 - 70||100|