Wafer Bonding Feedback Control for Overlay Distortion Mitigation
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Solution Overview
Problem
Traditional methods for controlling bonding tools to minimize overlay distortions in wafer pairs are outdated and unable to account for new adjustment technologies, leading to reliability concerns and potential electrical discontinuities.
Innovation Solution
A system and method that includes a wafer shape metrology sub-system for measuring pre- and post-bonding wafers, a controller to apply a bonder control model to measured distortions, and provide feedback adjustments to the bonding tool to maintain tolerance limits, using algorithms like PCA to generate orthogonal wafer signatures for precise adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional control methods are used for bonding tools, then the system is simple and easy to operate, but overlay distortion patterns cannot be minimized effectively
Solution Approach 1:
The patent implements a feedback control system where wafer shape measurements are taken before and after bonding, the differences are analyzed to determine distortion patterns, and control adjustments are automatically applied to the bonding tool based on these measurements. This closed-loop feedback mechanism enables precise overlay control while adapting to various distortion patterns.
Solution Approach 2:
The system changes multiple control parameters of the bonding tool simultaneously based on measured distortion patterns. By adjusting multiple parameters (such as heater zone temperatures, pressure distribution, or wafer positioning) in coordination, the system achieves precise overlay control that accounts for the complex interrelationships between different tool adjustments.
2Manufacturing precision
If new adjustment technologies are implemented in bonding tools, then overlay precision can be improved, but traditional control models become outdated and inadequate
Solution Approach 1:
The control model is designed to be dynamic and adaptive rather than static. It continuously updates based on actual measurements from the wafer shape metrology system, allowing the model to adapt to new adjustment technologies and evolving distortion patterns. The system learns from each bonding operation and adjusts its control strategy accordingly.
Solution Approach 2:
The control approach segments the overlay distortion problem into multiple independent distortion patterns or modes. By analyzing measurements and identifying distinct distortion patterns (such as bow, warp, or localized deformations), the system can apply targeted adjustments for each pattern type, making the control model versatile enough to handle various new adjustment technologies.
3Reliability
If overlay distortion is not minimized, then the bonding process is simple, but reliability concerns arise and electrical continuity is compromised
Solution Approach 1:
The system performs preliminary measurements and predictions before the actual bonding process. Wafer shape is measured before bonding, and the system predicts potential distortion patterns based on these pre-bonding measurements. Control adjustments are pre-calculated and applied before bonding occurs, preventing distortion rather than correcting it afterward, thus ensuring reliability without sacrificing productivity.
Data Source
AI summary
A system includes a wafer shape metrology sub-system configured to perform one or more shape measurements on post-bonding pairs of wafers. The system includes a controller communicatively coupled to the wafer shape metrology sub-system. The controller receives a set of measured distortion patterns. The controller applies a bonder control model to the measured distortion patterns to determine a set of overlay distortion signatures. The bonder control model is made up of a set of orthogonal wafer signatures that represent the achievable adjustments. The controller determines whether the set of overlay distortion signatures associated with the measured distortion patterns are outside tolerance limits provides one or more feedback adjustments to the bonder tool.