Wafer Bowing: Causes and Solutions by Guy Landman and Hila Haimov
during the process thin films wafer become bowing and we are going to analyze why it happand
Wafer bowing happens because of three main reasons:
- Lack of technology- there are no tools to predict or monitor stress during the process.
- No clear standards = Each fab measures bowing differently, and there’s no agreement on what’s acceptable.
- Material issues -Different materials expand at different rates with heat, which causes stress and bending.
All these lead to unwanted wafer deformation.
Wafer bowing occurs during packaging and deposition
Analyze and control thermal stress during early stack design
3
High thermal stress between layers
Use materials with closely matched CTE values
0
Material combinations not selected by CTE compatibility
Create a validated material database with thermal/mechanical properties
5
No simulation is done before processing
Integrate stress modeling tools in early process design
2
Simulation tools are not used or available
Invest in tools and train engineers to use them
1
Lack of simulation tools and CTE-matching guidelines
Develop a unified design-simulation-material workflow
4
This tool will help us analyze practical ideas to reduce wafer bowing, ranked by implementation and validation difficulty.
If | symmetric deposition is applied to both sides of the wafer |
|---|---|
Then | bowing can be eliminated due to stress balance |
But | This solution increases both cost and process complexity |
Similar projects
Aluminum is common material used in the welding industry due to its suitable properties, Although aluminum welding generally has disadvantages. One of these weaknesses is the formation of porosity, which will affect the welded joint's mechanical properties. porosity is formed due to two mechanisms, shrinkage porosity caused by shrinkage during the metal solidification process and gas porosity caused by air trapping and undissolved hydrogen. The welding process often produces gases such as hydrogen, carbon dioxide and steam. During welding, the metal goes into a liquid state and then cools at a rapid rate. because In a liquid there is a higher solubility of a gas than in a solid, This may trap gases inside the material and create bubbles when the welding takes place. n order to minimize the problems with the porosity of the material due to welding, it is necessary to control the speed of the process, thermal gradient, dynamics of melt pool flow and solidification. Therefore, in order to solve this problem, we use laser beam welding.
אספקטים בשיפור עמידות של פותחני בקבוקים
