Electron Beam Exposure Dose Shaping for Line Width Uniformity
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Solution Overview
Problem
The resolution of electron beam lithography is limited by electron scattering, leading to variations in line width due to both short and long range scattering, resulting in poor uniformity and resolution of patterns.
Innovation Solution
A method for determining an exposure dose that involves defining an exposure region, a non-exposure region, and a marginal region, with a target dose in the exposure region that is higher than the non-exposure region, and optionally an intermediate region with a decreased dose, to increase the energy deposition gradient and improve pattern uniformity and resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a uniform exposure dose is applied across the exposure region, then the manufacturing process is simple, but the line width uniformity and pattern resolution deteriorate due to electron scattering
Solution Approach 1:
The patent applies local quality by dividing the exposure region into multiple zones (exposure region, non-exposure region, and marginal region) with different exposure doses. The marginal region receives a higher exposure dose than the interior exposure region to compensate for electron scattering effects at boundaries, while the non-exposure region receives minimal dose. This spatially varying dose distribution improves line width uniformity and pattern resolution without requiring complex additional equipment.
Solution Approach 2:
The patent changes the exposure dose parameter across different spatial locations within the exposure region. By increasing the exposure dose in the marginal region adjacent to the non-exposure region, the patent compensates for the energy deposition variations caused by electron scattering at region boundaries. This parameter modification directly addresses the line width uniformity issue while maintaining a relatively simple exposure apparatus.
2Manufacturing precision
If the exposure dose is increased to improve pattern resolution, then the pattern quality improves, but the energy consumption and resist material damage increase
Solution Approach 1:
The patent applies local quality by selectively increasing the exposure dose only in the marginal region where it is most needed for pattern resolution, rather than uniformly increasing the dose across the entire exposure region. This localized approach improves pattern resolution at critical boundaries while minimizing unnecessary energy deposition in regions where adequate resolution is already achieved, thus reducing overall energy consumption and resist material damage.
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 uniformity and resolution of patterns by adjusting the exposure dose, resulting in improved quality and wider application of resist materials in photomask manufacturing.
Implementation Method 1
The resolution of electron beam lithography is limited by electron scattering, leading to variations in line width due to both short and long range scattering
Data Source
AI summary
A method of determining an exposure dose for writing a pattern using an electron beam writer determines a target dose in the exposure region to obtain a predetermined energy deposition in a specific position of the exposure region, the predetermined energy deposition being larger than a reference energy deposition in the non-exposure region. The target dose is locally increased in a marginal region of the exposure region (the marginal region being adjacent the exposure boundary) to a value that obtains an energy deposition in the marginal region higher than the predetermined energy deposition. Optionally, the target dose can be locally decreased in an intermediate region of the exposure region (the intermediate region being adjacent the marginal region) to a value that obtains an energy deposition in the intermediate region smaller than the predetermined energy deposition. Also provided is an exposure device for carrying out the method.