Photomask Assembly Layout for Offset-Tolerant Patterned Masks
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Solution Overview
Problem
The formation of patterned masks on semiconductor substrates is complex and prone to yield loss due to photomask offset, leading to incomplete patterns and increased manufacturing defects.
Innovation Solution
A photomask assembly comprising a first, second, and third photomask is used to form a patterned mask, where the first photomask ensures a greater distance between strip-shaped patterns at the boundary, and the second photomask ensures a greater distance between the opening edge and neighboring patterns, reducing the likelihood of incomplete patterns even with photomask offset.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional photomask design is used, then manufacturing process is simple, but yield loss increases due to incomplete patterns when photomask offset occurs
Solution Approach 1:
The photomask assembly is divided into multiple photomasks (first photomask, second photomask, third photomask), each responsible for forming specific patterned structures. This segmentation allows each photomask to be optimized independently for its specific function, improving overall pattern completeness while managing complexity through modular design
Solution Approach 2:
The first photomask pre-forms a first patterned structure with strategically designed strip-shaped patterns that create buffer zones. This preliminary action ensures that even if subsequent photomasks have offset, the fundamental pattern framework is already in place, preventing incomplete patterns and reducing yield loss
2Manufacturing precision
If photomask offset occurs, then manufacturing process remains unchanged, but pattern precision deteriorates leading to yield loss
Solution Approach 1:
The strip-shaped patterns in the first patterned structure are designed with non-uniform spacing - the distance between strip-shaped patterns at boundary regions is deliberately made greater than the distance in central regions. This local quality variation creates buffer zones at boundaries that tolerate photomask offset, maintaining pattern position accuracy and preventing yield loss
Solution Approach 2:
The increased distance between strip-shaped patterns at boundary regions serves as a pre-established cushion or buffer zone. When photomask offset occurs, this buffer absorbs the positional deviation, ensuring that patterns remain complete and precise, thereby maintaining productivity despite the offset
3Reliability
If second photomask is designed with standard margins, then manufacturing is straightforward, but offset tolerance is insufficient causing incomplete patterns
Solution Approach 1:
The second photomask is designed with modified parameters - the distance between the opening edge of the second patterned structure and neighboring strip-shaped patterns is intentionally increased beyond standard margins. This parameter change enhances offset tolerance, ensuring that even with photomask misalignment, the second patterned structure maintains sufficient clearance to prevent incomplete patterns
Data Source
AI summary
A photomask assembly includes: a first photomask for forming a first patterned structure, the first patterned structure having a first patterned opening which includes a plurality of strip-shaped patterns, a distance between the strip-shaped patterns at the two sides of a boundary between the first region and the second region being greater than a distance between other every two neighboring strip-shaped patterns when the center of the first photomask coincides with the center of the substrate; and a second photomask for forming a second patterned region which covers a first patterned opening of a second region, a distance between an opening edge of the second patterned structure and the neighboring strip-shaped pattern being greater than a first preset distance when the center of the second photomask and the center of the first photomask coincide with the center of the substrate.