Back-Side Wafer Trenches for Stress-Induced Bow Control
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Solution Overview
Problem
Wafer bowing caused by stresses induced during front-side processing operations leads to unevenness and die defects, as existing technologies fail to effectively predict and mitigate these stresses before subsequent processing steps.
Innovation Solution
A wafer modification system generates a compensation map based on characteristic data to identify regions where back-side trenches can be formed to reduce predicted bowing, initiating their formation before front-side processes are completed, thereby proactively addressing stress-induced wafer unevenness and improving thermal characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If front-side processing operations are completed on the wafer, then electronic circuits are formed on the front side, but stress-induced wafer bowing occurs leading to unevenness and die defects
Solution Approach 1:
The system performs back-side trench formation before front-side processing is completed. By proactively forming trenches in regions predicted to experience high stress based on characteristic data and compensation maps, the system prevents wafer bowing before it occurs during subsequent front-side processing operations, thereby maintaining wafer flatness and preventing die defects
Solution Approach 2:
The system applies counter-action by forming back-side trenches in advance to offset the stress that will be induced by front-side processing operations. The compensation map identifies specific regions where trenches should be formed to create opposing stress relief, counteracting the bowing effect before it manifests during front-side processing
2Manufacturing precision
If back-side trenches are formed to reduce wafer bowing, then wafer flatness is improved, but additional processing steps are required
Solution Approach 1:
The back-side trench formation is performed early in the process sequence, before front-side processing is completed. This preliminary action integrates the stress relief step into the existing process flow without requiring separate post-processing operations, thereby managing complexity through proactive integration
Solution Approach 2:
The system forms trenches only in specific regions identified by the compensation map based on characteristic data. Rather than uniformly processing the entire wafer back side, trenches are selectively formed in high-stress regions, optimizing the balance between achieving flatness improvement and minimizing additional processing complexity
Data Source
AI summary
A method can include obtaining characteristic data for a wafer. The characteristic data can correspond to the wafer in a processed state and can include a set of stress values of the wafer. The wafer can include a front side, a back side opposite the front side, and a set of regions. The set of stress values can include a first stress value corresponding to a first region. In the processed state, one or more front-side processes can be completed on the front side of the wafer. The method can include determining that the first stress value exceeds a stress threshold and generating a compensation map. The compensation map can identify one or more regions for forming one or more trenches. The method can include initiating, based on the compensation map, a formation of a first trench on the back side of the wafer in the first region.