Dynamic Wafer Bonding Gap Control for Stress-Residue Reduction
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Solution Overview
Problem
Wafer bonding processes face challenges with residual stress in bonded wafers due to uneven bonding wave propagation, leading to deformation and issues in subsequent processes like photo lithography and planarization.
Innovation Solution
Implementing dynamic bond gap control during wafer bonding by dynamically adjusting the stage gap between wafer stages as the bonding wave propagates, using motors and optical devices to maintain a consistent slant angle and reduce the radius of curvature, thereby minimizing stress residue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the stage gap is kept constant during bonding wave propagation, then the bonding process is simple to control, but the radius of curvature of bent wafer portions decreases leading to increased stress residue
Solution Approach 1:
The stage gap is dynamically adjusted during the bonding wave propagation process rather than kept constant. The controller modifies the gap between first and second wafer stages in real-time as the bonding wave moves from center to edge, which maintains a substantially constant slant angle and prevents excessive reduction in radius of curvature, thereby reducing stress residue while managing process complexity through automated control.
Solution Approach 2:
The system uses optical devices to detect the position of the bonding wave front and provides feedback to the controller. Based on this feedback, the controller dynamically adjusts the stage gap to maintain optimal bonding conditions. This closed-loop control enables precise management of the bonding process while reducing stress residue through adaptive gap adjustment.
2Productivity
If the bonding wave propagates quickly from center to edge, then the bonding process is faster, but the slant angle of bent portions increases leading to deformation and stress residue
Solution Approach 1:
The stage gap is dynamically adjusted during the bonding wave propagation process rather than kept constant. The controller modifies the gap between first and second wafer stages in real-time as the bonding wave moves from center to edge, which maintains a substantially constant slant angle and prevents excessive reduction in radius of curvature, thereby reducing stress residue while managing process complexity through automated control.
Solution Approach 2:
The system changes the physical parameters of the bonding process dynamically - specifically adjusting the stage gap parameter as the bonding wave propagates. This parameter change maintains the slant angle within an optimal range, preventing wafer deformation and stress residue while allowing the bonding process to proceed efficiently.
3Manufacturing precision
If the slant angle of bent portions is reduced, then stress residue is minimized, but the bonding process requires complex dynamic gap adjustment
Solution Approach 1:
The system uses optical devices to detect the position of the bonding wave front and provides feedback to the controller. Based on this feedback, the controller dynamically adjusts the stage gap to maintain optimal bonding conditions. This closed-loop control enables precise management of the bonding process while reducing stress residue through adaptive gap adjustment.
Solution Approach 2:
The patent replaces manual or simple mechanical gap adjustment with an automated control system that uses optical detection and electronic control. The controller receives optical signals about bonding wave position and automatically adjusts the stage gap, substituting complex manual mechanical operations with an integrated electromechanical control system.
Data Source
AI summary
A method includes placing a first wafer on a first wafer stage, placing a second wafer on a second wafer stage, and pushing a center portion of the first wafer to contact the second wafer. A bonding wave propagates from the center portion to edge portions of the first wafer and the second wafer. When the bonding wave propagates from the center portion to the edge portions of the first wafer and the second wafer, a stage gap between the top wafer stage and the bottom wafer stage is reduced.