Assistant Pattern Configuration for Lithographic Focal Plane Offset
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Solution Overview
Problem
In semiconductor manufacturing, the optical proximity effect causes distortions in lithographic patterns due to light diffraction, leading to degraded imaging quality, especially as design sizes shrink, and existing methods like sub-resolution assist features and optical proximity correction have limitations in maintaining pattern consistency across different directions.
Innovation Solution
An assistant pattern configuration method is introduced, where initial assistant patterns are configured around main patterns to adjust configuration parameters corresponding to optimal focal plane offsets, allowing for improved alignment of focal planes in different directions, thereby enhancing lithographic quality by increasing the process window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the design size of semiconductors continues shrinking, then the integration density increases, but the light diffraction effect becomes more obvious causing optical proximity effect and pattern distortion
Solution Approach 1:
The patent applies preliminary action by pre-configuring assistant patterns around main patterns before the actual lithography exposure. These assistant patterns are designed to compensate for the optical proximity effect that will occur during exposure, thereby improving pattern accuracy at scaled dimensions without requiring changes to the lithography system itself.
Solution Approach 2:
The patent implements local quality by introducing direction-dependent assistant patterns with different configuration parameters for different spatial directions. The configuration parameters (such as assistant pattern size and distance from main pattern) are adjusted based on the optimal focal plane offset in specific directions, creating locally optimized pattern compensation rather than uniform adjustment across the entire design.
2Measurement precision
If conventional assist features and OPC methods are used, then lithographic resolution is improved, but pattern consistency across different directions deteriorates due to optimal focal plane offset
Solution Approach 1:
The patent applies asymmetry by configuring assistant patterns with different parameters in different directions. Specifically, the configuration parameters of assistant patterns are adjusted according to the optimal focal plane offset in each direction, creating asymmetric compensation that matches the directional nature of the optical proximity effect. This ensures pattern consistency across different orientations by treating each direction according to its specific optical characteristics.
3Reliability
If assistant patterns are added to improve lithographic quality, then the process window increases, but the device complexity increases
Solution Approach 1:
The patent applies partial action by selectively adding assistant patterns only where needed based on the optimal focal plane offset analysis. Rather than uniformly adding assistant patterns across the entire design, the method configures them with specific configuration parameters only in regions and directions where the optical proximity effect significantly impacts pattern accuracy, thereby balancing lithographic quality improvement with mask complexity management.
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
The method improves lithographic quality by reducing the offset between optimal focal planes in different directions, resulting in a larger process window and more accurate pattern transfer during exposure, maintaining pattern consistency across various orientations.
Implementation Method 1
as a design size of semiconductors continues shrinking towards the limit of a lithographic imaging system, and a light diffraction effect is more obvious
Data Source
AI summary
Embodiments and implementations of the present disclosure provide assistant pattern configuration methods, masks and forming methods thereof, and related devices. One form of a configuration method includes: providing a main pattern having an edge extending along a first direction, where a second direction is perpendicular to the first direction, the main pattern having a first optimal focal plane in the first direction and a second optimal focal plane in the second direction when exposed, and where there is an optimal focal plane offset between the first optimal focal plane and the second optimal focal plane; providing an initial assistant pattern around the main pattern; extracting a configuration parameter of the initial assistant pattern, the configuration parameter corresponding to the optimal focal plane offset; obtaining configuration information corresponding to a preset optimal focal plane offset based on an adjustment of the configuration parameter; and configuring an assistant pattern around the main pattern according to the configuration information. Embodiments and implementations of the present disclosure can improve lithographic quality.