Wafer bowing is a recurring problem in advanced semiconductor manufacturing, especially during thin film deposition and wafer-level packaging.
The bowing results from thermal expansion mismatch (CTE) and residual stress between deposited layers and the silicon substrate.
There are currently no standardized solutions to fully predict or prevent bowing, and most process tuning is done empirically.
Bowing greater than 50 µm can cause lithography misalignment, bonding failure, and tool clamping issues.
According to industry reports, bowing contributes to 15–20% yield loss in high-volume packaging lines, leading to significant production delays and financial costs.
The ultimate goal is to achieve effective control and reduction of wafer bowing during semiconductor manufacturing processes.
Wafer bowing due to CTE mismatch remains unpredictable, there is no reliable method to select material stacks that minimize thermal stress during the early design stages.
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.
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