Wafer Holder Surface Compensation for Submicron Alignment
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Solution Overview
Problem
Existing wafer alignment devices struggle to achieve precise alignment with distortion values better than 2µm, especially beyond the vicinity of alignment marks, due to limitations in controlling local and macroscopic distortions on wafer surfaces.
Innovation Solution
A receiving device with independent active control elements that can influence the holding surface's shape and temperature, using strain maps and position maps to compensate for local distortions, allowing for precise alignment by locally expanding or deforming the wafer through temperature control, piezo elements, and pressure adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional receiving devices with flat holding surfaces are used, then device simplicity is maintained, but alignment precision deteriorates due to uncorrected local and macroscopic wafer distortions
Solution Approach 1:
The holding surface is divided into multiple independently controllable zones or regions, each capable of local shape adjustment through piezoelectric actuators or thermal control elements. This segmentation allows targeted correction of local wafer distortions without requiring complete system redesign, thereby improving alignment precision while controlling complexity increase.
Solution Approach 2:
The holding surface transitions from a static flat surface to a dynamically adjustable surface that can adapt its shape in real-time. By incorporating controllable elements that respond to measured wafer distortion patterns, the system dynamically compensates for both local and macroscopic distortions, achieving sub-0.25µm alignment precision.
2Manufacturing precision
If the holding surface is made rigid and flat, then structural stability is maintained, but the ability to compensate for wafer distortions deteriorates
Solution Approach 1:
The holding surface incorporates elements that can change their physical parameters (shape, position) in response to measured wafer distortion patterns. Piezoelectric actuators and thermal control elements modify local surface geometry dynamically, enabling compensation of distortion while preserving overall structural stability through controlled, reversible parameter changes.
Solution Approach 2:
Different regions of the holding surface are equipped with independent control capabilities, allowing local adaptation to wafer distortion patterns. Each zone can be individually adjusted to match the local wafer topology, while the global structural stability is maintained through the rigid support framework and coordinated control of multiple zones.
3Manufacturing precision
If alignment accuracy is improved through active distortion compensation, then bonding quality improves, but the complexity of the control system increases
Solution Approach 1:
The system employs feedback control by measuring actual wafer position and distortion patterns using alignment marks and position maps, then using this information to drive compensation actions through piezoelectric or thermal actuators. This closed-loop feedback mechanism achieves high alignment accuracy while managing control complexity through systematic error correction based on actual measurements.
Solution Approach 2:
The system performs self-correction by automatically measuring its own alignment errors through embedded sensors and alignment marks, then autonomously adjusting the holding surface shape to compensate for detected distortions. This self-service capability reduces the need for external intervention and simplifies the overall control architecture while maintaining sub-0.25µm alignment precision.
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
This approach enables alignment accuracy better than 0.25µm by minimizing local and macroscopic distortions, ensuring a flat holding surface and reducing the risk of unbonded areas during pre-bonding, thereby improving the overall alignment and bonding process.
Implementation Method 1
The temperature of the mounting surface can be locally influenced by the compensation means. A local temperature increase of the mounting surface leads to a local expansion of the wafer held on the mounting surface at that position.
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3a~3b
AI summary
The present invention relates to a receiving device for receiving and holding wafers, comprising: - a holding surface (10), - holding means for holding the wafer on the holding surface (10), and - compensation means (3, 4, 5, 6) for actively, at least partially, compensating for global distortions of the wafer, wherein the holding surface (10) can be locally pressurized, hydraulically and/or pneumatically, from a rear side (1r) of the holding surface (10) by the compensation means (3, 4, 5, 6). Furthermore, the present invention relates to a device and a method for aligning a first wafer with a second wafer using the aforementioned receiving device.