Pixel Irradiation Allocation for Electron Beam Writing Precision
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Solution Overview
Problem
The challenge in electron beam writing for semiconductor devices is the difficulty in achieving precise control of irradiation time at the pixel level due to fractional portions being shorter than the minimum control unit, leading to reduced writing precision and inability to effectively manage gray scale patterns and line width variations.
Innovation Solution
A data generating apparatus that calculates a target irradiation amount, rounds it to a control unit, and allocates differences across adjacent pixels to achieve precise irradiation, allowing for increased writing precision without reducing the minimum control unit of irradiation time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the minimum control unit of irradiation time is reduced to achieve precise gray scale control, then writing precision is improved, but device complexity and technical difficulty increase significantly
Solution Approach 1:
The patent merges multiple pixels into a single control unit (one-shot control region), treating them as a unified target for beam irradiation. Instead of controlling each pixel independently with fractional time units, the system controls groups of pixels simultaneously with a single irradiation event, thereby avoiding the need to reduce the minimum control unit period while still achieving effective gray scale control through spatial distribution of irradiation amounts.
Solution Approach 2:
The patent transitions from temporal control (fractional time units) to spatial control (distribution across multiple pixels). By allocating different irradiation amounts to different pixels within a control unit based on their positional relationships and proximity effects, the system achieves gray scale control through spatial variation rather than temporal subdivision, thus avoiding the technical difficulties of reducing the minimum control unit period.
2Manufacturing precision
If fractional irradiation times shorter than the minimum control unit are used, then irradiation amount distribution control is improved, but the ability to apply electron beams for desired irradiation time is lost
Solution Approach 1:
The patent performs preliminary calculation of irradiation amounts for multiple pixels before actual beam irradiation. The data generating apparatus computes the optimal irradiation amount for each pixel considering proximity effects and spatial relationships, then prepares control data that allocates these amounts across pixels. This preliminary planning allows the system to achieve precise irradiation amount distribution without needing to execute fractional time controls during actual beam application.
Solution Approach 2:
The patent introduces control data as an intermediary between the desired irradiation pattern and the physical beam application. The control data encodes the calculated irradiation amounts for each pixel and translates them into actionable commands for the beam control apparatus. This intermediary layer allows the system to achieve precise irradiation control through discrete control units rather than requiring continuous fractional time control.
3Device complexity
If the minimum control unit of irradiation time is not reduced, then device simplicity is maintained, but writing precision for gray scale patterns deteriorates
Solution Approach 1:
The patent applies different irradiation amounts to different pixels within a control unit based on their local characteristics, such as position relative to the beam entry point and proximity to other pixels. By considering local variations in irradiation requirements and applying tailored irradiation amounts to each pixel through the control data, the system achieves high writing precision for gray scale patterns while maintaining a relatively simple control unit structure.
4Productivity
If multiple beams are applied simultaneously with multi-beam technique, then productivity is improved, but control of irradiation time for each pixel becomes more difficult
Solution Approach 1:
The patent merges the control of multiple beams by grouping multiple pixels into a single control unit that is irradiated in one shot. Instead of independently controlling the irradiation time for each beam to each pixel, the system controls the simultaneous irradiation of multiple pixels with different irradiation amounts through a unified control mechanism, thereby simplifying the blanking control while maintaining multi-beam productivity.
Data Source
AI summary
In one embodiment, a data generating apparatus generates data including an irradiation amount of a beam in each pixel for an energy beam writing apparatus. The data generating apparatus includes a target irradiation amount calculating section configured to calculate a first irradiation amount in each pixel, an irradiation amount rounding section configured to round the first irradiation amount based on an irradiation amount control unit and calculate a second irradiation amount, a difference calculating section configured to calculate a first difference between the first irradiation amount and the second irradiation amount, a difference sum calculating section configured to calculate a sum of the first differences in a first group of a plurality of adjacent pixels, and an allocating section configured to allocate an irradiation amount based on the irradiation amount control unit and the sum to a pixel in the first group.