Redistribution Line Stitching for Fine and Coarse Interposer Routing
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Solution Overview
Problem
In the packaging of integrated circuits, the formation of larger interposers with increased functionality poses challenges in creating fine and coarse redistribution lines efficiently, as existing methods require multiple photolithography masks and processes, making it difficult to achieve precise routing and scaling.
Innovation Solution
The method involves using two photolithography masks with different reticle fields to perform two light-exposure processes on a photoresist, where the outer region forms coarse redistribution lines and the inner region forms fine redistribution lines, with a ring-shaped stitching region for alignment, allowing for the formation of redistribution lines with varying widths and pitches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple photolithography masks and processes are used to form redistribution lines, then routing precision can be achieved, but the process complexity and manufacturing difficulty increase significantly
Solution Approach 1:
The patent segments the photoresist exposure process into two distinct regions: an outer region exposed through a first photolithography mask for coarse redistribution lines, and an inner region exposed through a second photolithography mask for fine redistribution lines. This segmentation allows different line types to be formed in a single integrated process step, reducing overall process complexity while maintaining routing precision.
Solution Approach 2:
The patent merges the formation of coarse and fine redistribution lines into a single photolithography process by using two masks simultaneously. The outer region and inner region are exposed in the same process step, combining what would traditionally require separate processing steps into one unified operation, thereby simplifying the manufacturing process.
2Adaptability or versatility
If the interposer size is increased to integrate more functions, then packaging functionality improves, but the difficulty of forming precise redistribution lines increases
Solution Approach 1:
The patent applies local quality by providing different redistribution line characteristics in different regions of the interposer. The outer region receives coarse redistribution lines with larger widths and pitches suitable for peripheral routing, while the inner region receives fine redistribution lines with smaller widths and pitches for dense internal routing. This localized differentiation maintains manufacturing precision across the entire large interposer structure.
Solution Approach 2:
The patent introduces a spatial dimension to the photolithography mask design by creating concentric regions (outer and inner) with different exposure characteristics. This dimensional approach allows the single photolithography process to accommodate varying line requirements across different zones of the enlarged interposer, maintaining precision despite the increased overall size.
3Productivity
If a single photolithography process is used for both coarse and fine lines, then manufacturing efficiency improves, but the ability to achieve both line types with different widths and pitches becomes difficult
Solution Approach 1:
The patent changes the parameters of the photolithography masks to accommodate different line requirements. The first mask is configured with patterns for coarse lines with larger widths and pitches in the outer region, while the second mask is configured with patterns for fine lines with smaller widths and pitches in the inner region. By varying mask parameters rather than process parameters, the system achieves both line types efficiently in a single process.
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 simplifies the formation of redistribution lines by reducing the number of required photolithography processes while enabling precise routing and scaling, allowing for the creation of both fine and coarse lines within the same redistribution layer, enhancing the packaging efficiency and flexibility.
Implementation Method 1
forming a photoresist, and light-exposing the photoresist through a first light-exposure process and a second light-exposure process
Implementation Method 2
The first light-exposure process is performed using a first photolithography mask, wherein an outer region of the photoresist is exposed to form patterns
Data Source
AI summary
A method includes forming a photoresist on a base structure, and performing a first light-exposure process on the photoresist using a first lithography mask. In the first light-exposure process, an inner portion of the photoresist is blocked from being exposed, and a peripheral portion of the photoresist is exposed. The peripheral portion encircles the inner portion. A second light-exposure process is performed on the photoresist using a second lithography mask. In the second light-exposure process, the inner portion of the photoresist is exposed, and the peripheral portion of the photoresist is blocked from being exposed. The photoresist is then developed.