Semiconductor Pad Layout Using SADP to Cut Photomask Count
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Solution Overview
Problem
In semiconductor structures like DRAM, the use of multiple photomasks to form smaller sized pads increases production costs, necessitating a reduction in the number of photomasks required for the pad formation process.
Innovation Solution
A semiconductor structure and manufacturing method utilizing a self-alignment double patterning (SADP) process to form multiple first and second pads with distinct top-view shapes, where a portion of the first pads surrounds the second pads, reducing the number of photomasks needed and production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If multiple photomasks are used to form smaller sized pads, then the pad size can be reduced, but the production cost increases
Solution Approach 1:
The pad formation process is segmented into two separate patterning steps (first pad pattern and second pad pattern) that are performed sequentially using the self-aligned double patterning technique. This segmentation allows each pattern to be formed with simpler photomasks while achieving the overall complex pad structure, thereby reducing the complexity and cost of individual photomasks while maintaining small pad sizes.
Solution Approach 2:
The first pad pattern is formed in advance as a preliminary structure before forming the second pad pattern. This preliminary action establishes a foundation that guides subsequent patterning steps, allowing the final pad structure to be achieved with reduced photomask requirements compared to forming all patterns simultaneously.
2Area of moving object
If multiple photomasks are used to form pads, then smaller sized pads can be achieved, but the number of photomasks increases
Solution Approach 1:
The complex pad pattern is divided into two separate but related patterns (first pad pattern and second pad pattern) that are formed in sequence. This segmentation reduces the complexity of individual photomasks needed for each step compared to using a single complex photomask, while still achieving the desired small pad size through the combination of both patterns.
Solution Approach 2:
The first pad pattern acts as an intermediary structure that facilitates the formation of the second pad pattern. This intermediary approach allows the complex final pad structure to be built through simpler intermediate steps, reducing the overall photomask complexity required.
3Manufacturing precision
If traditional multi-photomask process is used, then pads can be formed, but the overlay window is reduced
Solution Approach 1:
The self-aligned double patterning technique merges the formation of the first and second pad patterns into a closely integrated process where the first pattern serves as a reference for the second pattern. This merging ensures precise spatial relationship between the two patterns, maintaining high manufacturing precision while simplifying the overlay requirements compared to traditional multi-photomask processes.
Data Source
AI summary
A semiconductor structure including a substrate, multiple first pads, and multiple second pads is provided. The first pads are disposed on the substrate and are separated from each other. The second pads are disposed on the substrate and are separated from each other. Each of the first pads and each of the second pads are separated from each other. A top-view shape of the each of the first pads is different from a top-view shape of the each of the second pads. A portion of the first pads surrounds the same second pad.