Wafer Bonder Leveling with Invar Shafts and Contact Sensors
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Solution Overview
Problem
Current semiconductor wafer bonding technologies face challenges in achieving precise alignment, uniform bond strength, and consistent leveling, which affect the quality and yield of semiconductor devices.
Innovation Solution
A wafer bonder apparatus with a lower and upper chuck, a process chamber, and three adjustment mechanisms for leveling, force balancing, and substrate contact sensing, utilizing Invar feed-through shafts for thermal stability and micrometer-based leveling, along with contact sensors and tension springs for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional wafer bonding technologies are used, then the bonding process can be completed, but the alignment precision and bond strength uniformity are insufficient
Solution Approach 1:
The patent applies parameter changes by using micrometer-based adjustment mechanisms to precisely control the positioning of the upper chuck, enabling sub-micrometer alignment precision. The leveling screws and tension springs allow independent adjustment of vertical position and pre-load force, transforming the bonding process from conventional low-precision mechanical positioning to high-precision controlled positioning with measurable improvements in alignment accuracy and bond uniformity
Solution Approach 2:
The patent implements feedback through contact sensors that detect when the upper and lower wafers have made contact during the bonding process. This feedback mechanism allows the system to automatically adjust the upper chuck position to achieve consistent contact force and alignment, eliminating the need for manual trial-and-error adjustment and ensuring repeatable bond quality across multiple bonding operations
2Manufacturing precision
If manual adjustment methods are used for chuck positioning, then the device structure can be simple, but the leveling precision and repeatability are poor
Solution Approach 1:
The patent segments the adjustment mechanism into three independent adjustment units, each equipped with its own micrometer and leveling screws. This segmentation allows each unit to be adjusted independently without affecting the others, enabling precise control of the upper chuck's position and orientation. The modular design maintains relative simplicity while achieving high leveling precision through coordinated adjustment of multiple independent elements
Solution Approach 2:
The patent applies preliminary action by providing pre-adjusted micrometer mechanisms and tension springs that are pre-configured to provide controlled pre-load forces. The contact sensors are pre-positioned to detect wafer contact at the correct moment. These preliminary configurations eliminate the need for complex real-time calculations or adjustments during bonding, achieving high precision through pre-engineered mechanical advantage and predictable force application
3Stability of the object's composition
If thermal expansion is not compensated, then the device structure can be simpler, but the dimensional stability during bonding is poor
Solution Approach 1:
The patent directly addresses thermal expansion by incorporating Invar alloy components in the feed-through shafts and structural elements. Invar's exceptionally low coefficient of thermal expansion (approximately 1.2×10^-6 /K) compensates for thermal effects during the bonding process, maintaining dimensional stability of the chuck positioning system even when temperature fluctuations occur. This material selection provides passive thermal compensation without requiring active heating or cooling systems
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
Ensures reliable, high-precision, and repeatable positioning of semiconductor wafers, enhancing the quality and consistency of wafer-to-wafer bonds, thereby improving manufacturing efficiency and reducing costs.
Implementation Method 1
The feed-through shaft comprises a material having a coefficient of thermal expansion (CTE) less than 2×10^-6 K^-1. The feed-through shaft comprises Invar material.
Implementation Method 2
The component for leveling the upper chuck includes a micrometer, a micrometer shaft, a pivot arm, and a support plate. Rotational motion of the micrometer causes linear motion of the micrometer shaft and the linear motion of the micrometer shaft causes linear motion of the feed-through shaft
Implementation Method 3
Each adjustment mechanism includes a component for sensing contact to the upper chuck, a component for adjusting the pre-load force of the upper chuck, and a component for leveling the upper chuck.
Data Source
AI summary
A wafer bonder apparatus, includes a lower chuck, an upper chuck, a process chamber and three adjustment mechanisms. The three adjustment mechanisms are arranged around a top lid spaced apart from each other and are located outside of the process chamber. Each adjustment mechanism includes a component for sensing contact to the upper chuck, a component for adjusting the pre-load force of the upper chuck, and a component for leveling the upper chuck.