Multi-Exposure E-Beam Lithography for Resolution and Cycle Time
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Solution Overview
Problem
Current e-beam lithography methods face challenges in achieving high resolution and reducing cycle time while maintaining cost-effectiveness, particularly due to limitations in pattern contrast and exposure dosage for small feature sizes in IC fabrication.
Innovation Solution
The implementation of an electron-beam lithography system with a multi-beam mechanism and a control module that allows for multiple e-beam exposures with adjustable intensity and pattern processing to enhance contrast and imaging resolution, including shape and dose corrections to address proximity and loading effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If single e-beam lithography is used to achieve high resolution for small feature sizes, then imaging resolution is improved, but cycle time increases and fabrication cost increases
Solution Approach 1:
The patent divides the lithography process into multiple sequential exposure steps, each writing a different pattern to the same resist layer. Multiple e-beam systems operate in parallel, each writing its assigned pattern simultaneously. This segmentation allows the total writing time to be distributed across multiple systems, reducing the cycle time per system while maintaining high resolution through the use of multiple focused e-beam spots.
2Productivity
If multiple e-beam lithography is used to reduce cycle time, then productivity is improved, but exposure dosage control is limited to single exposure
Solution Approach 1:
The patent implements different exposure dosages for different patterns by controlling the beam current and number of passes for each specific pattern. The first pattern receives a first exposure dosage, and the second pattern receives a second exposure dosage, allowing optimization of exposure parameters for different feature types, densities, and critical dimensions. This local quality control enables better pattern contrast and process window for hot spots in the IC design layout.
3Productivity
If raster-scan multiple e-beam lithography is used to reduce cycle time, then productivity is improved, but pattern contrast deteriorates for hot spots
Solution Approach 1:
The patent dynamically adjusts exposure parameters including beam current, number of passes, and scanning speed for different patterns based on their specific requirements. The system can vary the dosage dynamically across different regions of the wafer, allowing optimization of pattern contrast for hot spots while maintaining high productivity through parallel processing. This dynamic control enables adaptation to local pattern characteristics.
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 enables improved imaging quality and reduced cycle time by achieving multiple exposure dose levels, enhancing contrast and throughput in IC pattern formation without increasing fabrication costs.
Implementation Method 1
An electron-beam (e-beam) system is introduced for lithography patterning processes as the electron beam has wavelengths that can be tuned to very short, resulting in very high resolution
Data Source
AI summary
The present disclosure provides a method for electron-beam (e-beam) lithography patterning. The method includes forming a resist layer on a substrate; performing a first e-beam exposure process to the resist layer according to a first pattern; performing a second e-beam exposure process to the resist layer according to a second pattern, wherein the second patterned is overlapped to the first pattern on the resist layer; and developing the resist layer.