Reticle Opacity Layout for Single-Dose Multi-Size Patterning
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Solution Overview
Problem
Existing reticle configurations struggle to effectively utilize a single dose of actinic radiation to pattern features of different sizes during integrated circuit fabrication, particularly in NAND memory production, due to differences in optimal radiation doses required for large and small features.
Innovation Solution
Incorporating Sub-Resolution Assist Features (SRAFs) into larger pattern features on reticles to balance the optimal dose of actinic radiation, allowing for precise patterning of both large and small features by modifying the configuration of these features to include a central region with different opacity than the outer region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single dose of actinic radiation is used for patterning, then the photo-processing step is simplified and productivity is improved, but manufacturing precision deteriorates because large and small features require different optimal doses
Solution Approach 1:
The reticle pattern features are assigned different opacities based on their size characteristics. Small features are assigned a first opacity while large features are assigned a second opacity, allowing each feature type to receive its optimal radiation dose through the same actinic radiation step, thereby maintaining manufacturing precision while improving productivity
2Manufacturing precision
If different opacity values are assigned to different pattern features, then patterning accuracy for both large and small features is improved, but reticle construction complexity increases
Solution Approach 1:
The patent applies parameter changes by modifying the opacity parameter of reticle pattern features based on their size. This allows the reticle to differentiate between small and large features through a single structural modification approach, balancing the improvement in patterning accuracy with manageable reticle construction complexity
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
Enables high-precision and accurate formation of both large and small target features in integrated circuits, improving integration levels by optimizing the actinic radiation dose for all features, thereby enhancing fabrication accuracy.
Implementation Method 1
a form of radiant energy is passed through a radiation-patterning tool and onto a radiation-sensitive material associated with a semiconductor wafer. The radiant energy can be referred to as actinic energy
Implementation Method 2
Each of the larger pattern features has a configuration that includes a central region and an outer region laterally surrounding the central region, with the central region being of different opacity than the outer region
Data Source
AI summary
Some embodiments include a reticle which includes first pattern features and second pattern features. A first optimal dose of actinic radiation is associated with the first pattern features and a second optimal dose of the actinic radiation is associated with the second pattern features. The second pattern features are larger than the first pattern features. Each of the second pattern features has a configuration which includes a central region laterally surrounded by an outer region, with the central region being of different opacity than the outer region. The configurations of the second pattern features balance the second optimal dose of the actinic radiation to be within about 5% of the first optimal dose of the actinic radiation. Some embodiments include photo-processing methods.