Wafer Bonding Pressure Differential for Bond Wave Defect Control
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Solution Overview
Problem
Conventional wafer-level bonding techniques face challenges in controlling the propagation of the bond wave, leading to defects such as bubbles and edge defects in the bonded semiconductor wafers due to entrapped air and difficulty in achieving adequate alignment.
Innovation Solution
A vacuum apparatus is positioned between the chucks securing the wafers, using localized vacuum guns, a vacuum disk, or a gas curtain to induce a pressure differential and control the bond wave, with in-situ monitoring to improve line yields by reducing voids and defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional wafer-level bonding techniques are used, then bonding can be achieved, but defects such as bubbles and edge defects occur due to entrapped air and difficulty in controlling bond wave propagation
Solution Approach 1:
The patent extracts and removes the harmful air pockets from the bonding interface by controlling the bond wave propagation to move air outward from the center toward the edges, where it can be expelled. This prevents entrapped air from remaining in the bonded region, thereby eliminating bubbles and edge defects while maintaining bonding quality.
Solution Approach 2:
The patent applies dynamic control of the bond wave propagation by using a moving pressure front that travels across the wafer surface. This dynamic approach allows real-time control of the bonding process, enabling the bond wave to propagate systematically and prevent defect formation while achieving reliable bonding.
2Strength
If bonding pressure is applied to join wafers, then wafer bonding is achieved, but alignment difficulty and edge defects occur due to uncontrolled bond wave propagation
Solution Approach 1:
The patent applies preliminary alignment actions before the main bonding pressure is applied. The system pre-positions the wafers and initiates bond wave propagation from the center outward, ensuring proper alignment is established before full bonding pressure engages. This prevents misalignment and edge defects while achieving strong wafer bonding.
Solution Approach 2:
The bonding process is segmented into distinct phases: initial contact, bond wave propagation from center to edge, and final bonding. This segmentation allows precise control at each stage, particularly during the propagation phase where alignment is critical, thereby achieving both strong bonding and high manufacturing precision.
3Area of stationary object
If uniform pressure is applied across the wafer, then bonding coverage is achieved, but bond wave control is difficult leading to defects
Solution Approach 1:
The patent applies local quality by creating a non-uniform pressure distribution that varies across the wafer surface. The pressure is highest at the center and decreases toward the edges, which controls the bond wave propagation direction and speed. This localized pressure control achieves complete bonding coverage while simplifying bond wave management and preventing defects.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces edge defects and achieves more uniform bonding by controlling the bond wave propagation, enhancing the quality of the bonded wafers.
Implementation Method 1
attracting the first and second workpieces toward one another from the propagation point due to a pressure differential between the propagation point and the peripheral region
Data Source
AI summary
The present disclosure, in some embodiments, relates to a workpiece bonding apparatus. The workpieces bonding apparatus includes a first substrate holder having a first surface configured to receive a first workpiece, and a second substrate holder having a second surface configured to receive a second workpiece. A vacuum apparatus is positioned between the first substrate holder and the second substrate holder and is configured to selectively induce a vacuum between the first surface and the second surface. The vacuum is configured to attract the first surface and the second surface toward one another.