Photomask Alignment Marks for Semiconductor Lithography
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In high integration semiconductor processes, achieving accurate alignment and monitoring of photolithographic processes is challenging due to the complexity and limited space on photomasks, which affects the yield and efficiency of wafer production.
Innovation Solution
A photomask design with alignment marks for the current layer, featuring a shape extra-scribe lane pattern that includes multiple sets of alignment marks on the inter-scribe and extra-scribe lanes, allowing for improved photomask area use efficiency and real-time monitoring of exposure shot map accuracy through parallel and vertical patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If extra-scribe lane patterns are added on all four edges of the photomask for alignment monitoring, then alignment accuracy is improved, but photomask area utilization deteriorates
Solution Approach 1:
The patent extracts the extra-scribe lane pattern from one of the four edges of the photomask, keeping it only on three edges. This removes unnecessary elements while preserving the essential alignment monitoring function, thereby improving area utilization without significantly compromising alignment accuracy.
Solution Approach 2:
Instead of implementing extra-scribe lane patterns on all four edges (excessive action), the patent applies them to only three edges (partial action). This partial implementation is sufficient for alignment monitoring while optimizing the use of photomask area for main patterns.
2Measurement precision
If multiple sets of alignment marks are placed on the photomask for real-time monitoring, then measurement capability is improved, but device complexity increases
Solution Approach 1:
The alignment marks on the three edges serve multiple functions: they monitor alignment accuracy, verify shot map location, and provide reference for process control. This multi-functionality reduces the need for additional separate monitoring structures, thereby limiting complexity increase.
Solution Approach 2:
The patent combines the alignment monitoring function with the extra-scribe lane structure, integrating multiple functions into a single structural element. This merging reduces the overall complexity compared to having separate alignment marks and extra-scribe lanes.
Data Source
AI summary
A photomask with alignment marks for the current layer is provided with four edges. The photomask includes main patterns, an inter-scribe lane pattern sited between the main patterns, an extra-scribe lane pattern only sited on the three edges of the photomask, a first set of alignment marks for the current layer on opposite edges having the extra-scribe lane patterns. The photomask further includes a second set of alignment marks for the current layer on opposite edges in which only one has the extra-scribe lane pattern, and they are placed on opposite locations in the inter-scribe lane pattern and the extra-scribe lane pattern, respectively. Moreover, each one of the second set of alignment marks for the current layer include multiple parallel patterns and at least one vertical pattern sited on at least one end of the parallel patterns which are parallel to an extended direction of the opposite edges.