Lithography Reticle Test Patterns for OPC Optimization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional photolithography processes, including optical proximity correction (OPC), face challenges in maintaining pattern fidelity and process control, especially with feature sizes below 1 micron, due to optical distortion and resist processing effects, which are exacerbated as semiconductor devices continue to shrink.
Innovation Solution
The use of comprehensive test patterns on reticles, including a variety of one-dimensional and two-dimensional structures, for process tuning and monitoring, allowing for the detection of problematic points on wafers and optimization of the lithography process, including specific structures such as Full dense line, Isolated line, and Semi-dense trench, to improve OPC effectiveness and photolithography process monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photolithography processes are used with feature sizes below 1 micron, then manufacturing precision deteriorates due to optical distortion and resist processing effects, but reducing feature size is necessary for continued semiconductor scaling
Solution Approach 1:
The patent applies optical proximity correction (OPC) techniques to pre-distort the reticle pattern before lithography, compensating for anticipated optical distortion and resist processing effects. This preliminary action ensures that the final printed pattern achieves the desired fidelity despite the physical limitations of small feature sizes.
Solution Approach 2:
The patent modifies reticle design parameters by adding auxiliary features such as scattering bars and adjusting pattern geometries to compensate for optical effects. These parameter changes enable maintainment of pattern fidelity at reduced feature sizes by counteracting diffraction and scattering effects.
2Reliability
If comprehensive test patterns with multiple structures are added to reticles for process monitoring, then process control improves, but reticle complexity increases
Solution Approach 1:
The patent segments the reticle into distinct functional regions: a first region containing the semiconductor circuit pattern and a second region containing comprehensive test patterns. This segmentation allows independent optimization of each region, enabling thorough process monitoring without significantly impacting the main circuit fabrication.
Solution Approach 2:
The test patterns in the second reticle region serve multiple functions: they monitor optical proximity correction effectiveness, track lithography process variations, validate pattern fidelity, and provide data for process tuning. This multi-functionality achieves comprehensive process control within a compact additional area.
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
These test patterns enable easy detection of process weaknesses and optimization of the photolithography process, ensuring improved pattern fidelity and process control, even at smaller feature sizes, by providing a comprehensive set of structures for monitoring and tuning, compatible with conventional technology without significant equipment modifications.
Implementation Method 1
When the radiation from the radiation source is directed onto the reticle, light passes through the glass (regions not having chromium patterns) projects onto the resist covered silicon wafer to produce photo-generated acid.
Implementation Method 2
The reticle is placed between a radiation source producing radiation of a pre-selected wavelength and a focusing lens, which may form part of a 'stepper' apparatus.
Implementation Method 3
As light passes through the reticle, it is refracted and scattered by the chromium edges.
Implementation Method 4
As light passes through the reticle, it is refracted and scattered by the chromium edges.
Implementation Method 5
resist processing effects during the bake process, such as nonlinear diffusion of the photo-generated acid, exacerbate the pattern distortion on the wafer.
Data Source
AI summary
A lithographic mask reticle includes a first mask region having a first mask pattern configured for use in fabrication of electronic circuit structures, and a second mask region having a second mask pattern configured for use in fabrication of test structures. The second mask pattern includes all categories of structural patterns containing in the first mask pattern.