Per-Die Digital Mask Alignment for Substrate Warpage Correction
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Solution Overview
Problem
Microlithography techniques face challenges in achieving high placement accuracy for masks forming individual dies on substrates, leading to connection misplacement and yield loss due to substrate warpage and die drift during pick-and-place operations, which limits throughput and increases costs.
Innovation Solution
A method involving a metrology system to detect die locations, skew, and warpage, followed by a digital lithography system for per-die digital mask alignment correction using local and global transformation models to correct pattern placement errors, ensuring accurate alignment and compensation for substrate warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional lithography is used for pattern formation, then the photolithography process can be completed, but placement accuracy deteriorates due to substrate warpage and die drift
Solution Approach 1:
The system performs preliminary detection of substrate warpage and die location using a metrology system before the photolithography process. This advance measurement allows the calculation of transformation models that compensate for warpage effects, enabling accurate pattern placement despite substrate deformation
Solution Approach 2:
The system uses measured substrate warpage data and die location information to calculate local and global transformation models. These transformation models provide feedback corrections that are applied to the photolithography pattern placement, continuously improving accuracy based on actual substrate conditions
2Manufacturing precision
If high placement accuracy is required for mask alignment, then connection precision is improved, but throughput decreases and cost increases
Solution Approach 1:
The system divides the substrate into multiple regions and calculates separate local transformation models for each die location. This segmentation allows parallel processing of different substrate regions, maintaining high throughput while achieving precise alignment for each individual die through dedicated transformation corrections
3Manufacturing precision
If substrate warpage is not compensated, then the process is simple, but pattern overlay accuracy deteriorates
Solution Approach 1:
The system transforms the pattern placement coordinates using calculated transformation models that account for substrate warpage. By changing the coordinate parameters through mathematical transformation rather than physical substrate manipulation, the system achieves accurate pattern overlay while keeping the correction mechanism computationally-based and relatively simple
Data Source
AI summary
In one embodiment of the invention, a method for correcting a pattern placement on a substrate is disclosed. The method begins by detecting three reference points for a substrate. A plurality of sets of three die location points are detected, each set indicative of an orientation of a die structure, the plurality of sets include a first set associated with a first dies and a second set associated with a second die. A local transformation is calculated for the orientation of the first die and the second on the substrate. Three orientation points are selected from the plurality of sets of three die location points wherein the orientation points are not set members of the same die. A first global orientation of the substrate is calculated from the selected three points from the set of points and the first global transformation and the local transformation for the substrate are stored.