Charged Particle Beam Exposure for Low-Backscatter Pattern Density
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Solution Overview
Problem
Charged particle beam lithography is time-consuming and costly due to the high dose required to expose complex patterns on surfaces like reticles and wafers, particularly for advanced semiconductor manufacturing where feature sizes approach the resolution limit of conventional optical lithography.
Innovation Solution
The method involves calculating a pre-proximity effect correction (PEC) maximum dose dynamically based on pattern density and introducing an artificial background dose in low-backscatter areas to reduce the overall dose required for exposure, thereby shortening the write time and improving dose margin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional charged particle beam lithography is used to expose complex patterns, then pattern transfer accuracy is maintained, but exposure time and cost increase significantly
Solution Approach 1:
The patent applies preliminary proximity effect correction (PEC) to calculate and apply dose adjustments before the actual exposure process. By pre-calculating the dose distribution required to compensate for backscatter and proximity effects, the system determines optimal exposure parameters in advance, enabling faster exposure while maintaining pattern transfer accuracy.
Solution Approach 2:
The patent dynamically adjusts exposure dose parameters based on local pattern density and backscatter characteristics. By changing the dose parameter according to spatial variations in pattern density, the system optimizes exposure time for different regions while maintaining consistent pattern transfer quality across the entire substrate.
2Manufacturing precision
If high dose is applied to ensure accurate pattern exposure, then manufacturing precision is improved, but exposure time and cost increase
Solution Approach 1:
The patent applies local quality by differentiating dose requirements across different regions of the substrate based on local pattern density. Areas with high pattern density receive adjusted doses compared to low-density areas, optimizing both precision and time. The system calculates local backscatter contributions and applies spatially varying dose corrections rather than using a uniform high dose across the entire substrate.
Solution Approach 2:
The system performs preliminary calculation of the required dose distribution before exposure, determining the precise dose needed for each region based on pattern density and backscatter modeling. This pre-determination of optimal dose parameters eliminates the need to apply excessive dose as a safety margin, reducing exposure time while maintaining dose accuracy.
3Reliability
If conventional exposure methods are used for low-density patterns, then sufficient backscatter is achieved, but dose margin decreases and exposure efficiency is reduced
Solution Approach 1:
The patent introduces an intermediary artificial background dose that simulates the presence of additional patterns in low-density regions. This artificial dose acts as a mediator to increase the effective backscatter in areas where natural backscatter is insufficient, improving dose margin without requiring actual additional patterns or increasing overall exposure time.
Solution Approach 2:
The system dynamically changes the dose parameter for low-density regions by adding an artificial background dose component. This parameter adjustment compensates for insufficient natural backscatter in sparse pattern areas, improving dose margin and exposure efficiency simultaneously by tailoring the dose to local density conditions.
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 reduces the exposure time and cost associated with charged particle beam lithography by optimizing the dose distribution, ensuring accurate and efficient pattern transfer on surfaces with improved dose margin and reduced manufacturing variations.
Implementation Method 1
charged particle beams shoot energy to a resist-coated surface to expose the resist
Implementation Method 2
A backscatter for a sub area is calculated, based on the original set of exposure information
Data Source
AI summary
Methods for exposing a desired shape in an area on a surface using a charged particle beam system include determining a local pattern density for the area of the desired shape based on an original set of exposure information. A backscatter for a sub area is calculated, based on the original set of exposure information. Dosage for at least one pixel in a plurality of pixels in the sub area is increased, in a location where the backscatter of the sub area is below a pre-determined threshold, thereby increasing the backscatter of the sub area. A pre-PEC maximum dose is determined for the local pattern density, based on a pre-determined target post-PEC maximum dose. The original set of exposure information is modified with the pre-PEC maximum dose and the increased dosage of the at least one pixel in the sub area to create a modified set of exposure information.