Electron Beam Exposure Mask Proximity Effect Correction
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Solution Overview
Problem
Existing electron beam exposure systems face challenges in correcting the proximity effect, which causes line width deviations in patterns due to uneven energy distribution, particularly in peripheral portions of device formation patterns, leading to inefficiencies and limitations in current correction methods such as GHOST exposure and variable-shaped exposure.
Innovation Solution
An electron beam exposure system with a mask having opening portions that change in size at a predetermined rate, allowing for precise correction of the proximity effect in peripheral portions using a cell projection method, where the exposure can be adjusted by shifting the electron beam or focusing it out of focus to achieve energy planarization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If variable-shaped exposure is used to correct proximity effect by changing irradiation time for each pattern, then manufacturing precision of pattern dimensions is improved, but productivity deteriorates due to enormous exposure time required
Solution Approach 1:
The exposure field is divided into multiple sub-fields, and the exposure is performed by sequentially scanning these sub-fields across the substrate. This segmentation allows the system to achieve variable-shaped exposure effects while maintaining high productivity through efficient field utilization.
Solution Approach 2:
The invention employs dynamic field shifting and scanning mechanisms to adjust the exposure distribution dynamically. By controlling the relative movement between the exposure field and substrate, the system can compensate for proximity effects without requiring individual pattern-by-pattern exposure adjustments.
2Productivity
If cell projection method is used to simultaneously transfer patterns, then productivity is improved, but manufacturing precision deteriorates because irradiation time cannot be changed for each individual pattern in peripheral portions
Solution Approach 1:
The invention applies different exposure strategies to different regions of the substrate. By identifying peripheral portions with accumulated energy slopes and applying targeted field shifting and scanning operations to these specific regions, the system maintains uniform pattern dimensions across the entire substrate while preserving the efficiency of simultaneous pattern transfer.
3Manufacturing precision
If GHOST exposure is used to correct proximity effect by exposing auxiliary pattern outside device formation pattern, then manufacturing precision is improved, but device complexity increases due to requirement of additional exposure steps and space
Solution Approach 1:
The invention integrates proximity effect correction functionality into the standard exposure process by utilizing field shifting and scanning operations that are already part of the cell projection method. This multi-functional approach allows the same exposure system to simultaneously perform pattern transfer and proximity effect correction without requiring separate auxiliary exposure steps or additional equipment.
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 solution enables efficient correction of the proximity effect in peripheral portions, allowing for precise pattern formation without the need for multiple masks or extensive exposure time, and can handle varying energy slopes, resulting in consistent line widths and desired pattern shapes.
Implementation Method 1
electron beam exposure systems have come to be used in order to form fine patterns in lithography processes
Implementation Method 2
the amounts of energy received from the back scattering of incident electrons are different between inner patterns and peripheral patterns
Data Source
AI summary
An electron beam exposure system is designed to correct a proximity effect. The electron beam exposure system includes: an electron beam generation unit for generating an electron beam; an electron beam exposure mask having opening portions that are arranged so that sizes of the opening portions change at a predetermined rate in order of arrangement; a mask deflection unit for deflecting the electron beam on the electron beam exposure mask; a substrate deflection unit for deflecting and projecting the electron beam onto a substrate; and a control unit for controlling deflection amounts in the mask deflection unit and the substrate deflection unit. The direction or directions of the change may be any one of a row direction and a column direction or may be the row and column directions.