Wafer Alignment Using Pivot, Stop, and Bias Notches
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Challenges arise in aligning and assembling wafers with features, particularly when feature sizes become smaller, as precise positioning and alignment become increasingly difficult, affecting wafer processing, feature formation, and fixturing during alignment and assembly operations.
Innovation Solution
The method involves forming pivot-notches, stop-notches, and bias-notches on wafers to facilitate alignment using a two-contact and single-contact element system, with a biasing force applied to align features, and a system comprising a notching station to form these notches and a bonding station to secure the wafers after alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional alignment methods are used for wafers with smaller features, then alignment precision deteriorates, but implementing new notch-based alignment systems increases device complexity
Solution Approach 1:
The alignment system is segmented into distinct functional notches (pivot-notch, stop-notch, bias-notch) that separate different alignment functions. This allows each notch to be optimized for its specific purpose while maintaining overall system manageability despite increased complexity
Solution Approach 2:
The notch structure acts as an intermediary element between the wafer and the alignment fixture. The two-contact element and single-contact element interact with the notches to transmit alignment forces indirectly, improving precision while isolating the complexity within the notch geometry rather than the entire alignment system
2Manufacturing precision
If precise alignment is achieved through multiple contact points, then alignment accuracy improves, but the difficulty of detecting and measuring feature positions increases
Solution Approach 1:
The notches are pre-formed on the wafer at specific locations and orientations before the alignment process. This preliminary structuring of reference points simplifies the detection and measuring process during alignment, as the contact elements simply need to engage with the pre-defined notch geometries rather than detect arbitrary feature positions
3Manufacturing precision
If traditional fixturing methods are used for wafer assembly, then assembly simplicity is maintained, but assembly precision deteriorates with smaller features
Solution Approach 1:
The fixturing system applies localized quality through specifically designed contact elements that interact with corresponding notches. The two-contact element engages with the pivot-notch while the single-contact element engages with the stop-notch, creating localized high-precision interaction zones that maintain overall process simplicity
Data Source
AI summary
Wafers are aligned with one another by reference to features formed on or in each wafer. A method includes forming a first pivot-notch, a first stop-notch, and a first bias-notch in a first wafer by reference to first features formed on or in the first wafer. Also formed is a second pivot-notch, a second stop-notch, and a second bias-notch in a second wafer by reference to second features formed on or in the second wafer. A first wafer is mounted in an aligning device, wherein a two-contact element enters into the first pivot-notch, and a single-contact element enters the first stop-notch. The second wafer is mounted in the aligning device, wherein the two-contact element enters into the second pivot-notch, and the single-contact element enters the second stop-notch. A biasing force is exerted onto surfaces of the first and second bias-notches to align the first features with the second features.