Anamorphic Photolithography Layout Transfer Without Mask Replacement
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Solution Overview
Problem
Current photolithography methods for semiconductor manufacturing require multiple exposure processes using different photomasks, which increases processing time due to the need for mask replacement, especially when dealing with high numerical aperture (NA) systems that exacerbate the mask 3D effect and reduce resolution.
Innovation Solution
A photolithography method utilizing an anamorphic lens system within the projection optical system, allowing for two exposure processes to be performed using the same photomask without replacement, where the relative position of the photomask is changed to transfer patterns to both halves of the wafer, ensuring pattern layouts are substantially the same across the wafer except at the boundary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple exposure processes using different photomasks are performed, then complete pattern transfer is achieved, but processing time increases due to mask replacement
Solution Approach 1:
The exposure process is segmented into two sequential exposures using the same photomask. The first exposure transfers patterns to a first half field of the wafer, and the second exposure transfers patterns to a second half field. This segmentation allows complete pattern transfer without requiring multiple different photomasks, thereby eliminating mask replacement time while maintaining manufacturing precision.
Solution Approach 2:
The same photomask is used for multiple functions - transferring patterns to both the first half field and the second half field of the wafer. This multi-functionality eliminates the need for multiple specialized photomasks and the time-consuming replacement operations between them, resolving the contradiction between complete pattern transfer and processing time.
2Manufacturing precision
If high numerical aperture (NA) is used to increase resolution, then pattern resolution improves, but mask 3D effect increases
Solution Approach 1:
The patent performs two sequential exposure processes using the same photomask without interruption or replacement. This continuous action allows the system to maintain high NA settings throughout both exposures, maximizing resolution while managing the mask 3D effect through consistent optical conditions rather than changing masks between exposures.
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 reduces processing time by eliminating the need for mask replacement and maintains pattern consistency across the wafer, improving efficiency and resolution in semiconductor device manufacturing.
Implementation Method 1
The projection optical system may include an anamorphic lens having a reduction rate in the y-direction twice a reduction rate in the x-direction
Implementation Method 2
A first exposure process may be performed using the photomask to transfer layouts of patterns included in the photomask to a first half field of the wafer
Data Source
AI summary
A photolithography system includes a light source, a photomask stage, a projection optical system and a wafer stage, and the projection optical system includes an anamorphic lens. In a photolithography method, a wafer and a photomask are mounted on the wafer stage and the photomask stage, respectively, and a first exposure process is performed using the photomask to transfer layouts of patterns included in the photomask to a first half field of the wafer. A relative position of the photomask with respect to the wafer is changed, and a second exposure process is performed to transfer the layouts of the patterns included in the photomask to a second half field of the wafer.