Variable Dosage Charged Particle Beam Lithography for Sub-Resolution Pattern Formation
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Solution Overview
Problem
Conventional charged particle beam lithography systems face challenges in accurately forming reticle patterns with sub-resolution lithographic features, particularly due to the complexity and laboriousness of adding OPC features, which increases the feature count and costs, and struggles with maintaining precision as process nodes shrink, leading to manufacturing variations and critical dimension variations.
Innovation Solution
A method and system for determining a set of shaped beam shots that provide different dosages to various parts of the pattern, with calculated dose margins, allowing for overlapping shots to improve accuracy and reduce dimensional changes associated with process variations, and using techniques like partial exposure and dosage adjustment to optimize edge slope and reduce backscatter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional optical lithography is used to fabricate semiconductor devices, then the manufacturing process is straightforward, but manufacturing precision deteriorates at advanced technology nodes with sub-resolution features
Solution Approach 1:
The patent replaces conventional optical lithography with charged particle beam lithography (electron beam or ion beam) to achieve sub-resolution pattern formation. The charged particle beam system uses direct-write or mask-based approaches with controlled beam dosage to form patterns that are smaller than the optical resolution limit, thereby improving manufacturing precision at advanced technology nodes.
Solution Approach 2:
The patent employs variable dosage techniques where different amounts of charged particle beam exposure are applied to different regions of the pattern. By adjusting beam dosage parameters, the system can control pattern formation in overlapping exposure regions, enabling precise control of critical dimensions and edge slopes while maintaining manufacturing feasibility.
2Manufacturing precision
If OPC features are added to reticle patterns, then pattern accuracy improves, but the feature count increases and manufacturing becomes more laborious
Solution Approach 1:
The charged particle beam lithography system performs self-correction of pattern distortions through controlled overlapping exposures and variable dosage techniques. The system inherently compensates for proximity effects and optical distortions by adjusting beam dosage in different regions, eliminating the need for separate OPC feature addition and reducing manufacturing complexity.
Solution Approach 2:
The patent applies proximity effect correction and dosage optimization in advance during the mask data preparation stage. By pre-calculating and applying appropriate dosage variations to different pattern regions before exposure, the system prevents pattern distortion rather than correcting it afterward, thereby improving accuracy while simplifying the manufacturing process.
3Productivity
If process nodes are shrunk to increase device density, then productivity improves, but manufacturing precision deteriorates due to increased variations
Solution Approach 1:
The patent applies local quality control through spatially variable beam dosage where different regions of the pattern receive different exposure doses. This allows precise control of critical dimensions in high-density areas by adjusting dosage locally, compensating for proximity effects and maintaining manufacturing precision even as device density increases at shrunk process nodes.
4Manufacturing precision
If charged particle beam lithography is used, then sub-resolution patterns can be formed, but backscatter effects increase and reduce pattern accuracy
Solution Approach 1:
The patent converts the harmful backscatter effect into a beneficial tool by deliberately using overlapping charged particle beam exposures. The backscatter from previously exposed regions contributes to the dosage in overlapping areas, and by carefully controlling the overlap and dosage parameters, the system achieves precise pattern formation while accounting for and utilizing the backscatter effect rather than treating it purely as a disturbance.
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 enhances the accuracy and reduces dimensional changes in the written pattern, improves edge slope, and decreases the effects of backscatter, thereby improving the precision and efficiency of pattern formation on reticles, especially at advanced technology nodes.
Implementation Method 1
a charged particle beam writer is used to write desired patterns of a layer directly on the surface
Implementation Method 2
different dosages to different parts of the pattern, and where the dose margin from the set of shots is calculated
Data Source
AI summary
A method and system for fracturing or mask data preparation or optical proximity correction or proximity effect correction or mask process correction is disclosed in which a set of shaped beam shots is determined that is capable of forming a pattern on a surface, where the set of shots provides different dosages to different parts of the pattern, and where the dose margin from the set of shots is calculated. A method for forming patterns on a surface is also disclosed.